| Message ID | 20241223-preset_v2-v3-2-a339f475caf5@oss.qualcomm.com |
|---|---|
| State | New |
| Headers | show |
| Series | PCI: dwc: Add support for configuring lane equalization presets | expand |
On Mon, Dec 23, 2024 at 08:02:23PM +0530, Krishna Chaitanya Chundru wrote: > > > On 12/23/2024 5:17 PM, Dmitry Baryshkov wrote: > > On Mon, Dec 23, 2024 at 12:21:15PM +0530, Krishna Chaitanya Chundru wrote: > > > PCIe equalization presets are predefined settings used to optimize > > > signal integrity by compensating for signal loss and distortion in > > > high-speed data transmission. > > > > > > As per PCIe spec 6.0.1 revision section 8.3.3.3 & 4.2.4 for data rates > > > of 8.0 GT/s, 16.0 GT/s, 32.0 GT/s, and 64.0 GT/s, there is a way to > > > configure lane equalization presets for each lane to enhance the PCIe > > > link reliability. Each preset value represents a different combination > > > of pre-shoot and de-emphasis values. For each data rate, different > > > registers are defined: for 8.0 GT/s, registers are defined in section > > > 7.7.3.4; for 16.0 GT/s, in section 7.7.5.9, etc. The 8.0 GT/s rate has > > > an extra receiver preset hint, requiring 16 bits per lane, while the > > > remaining data rates use 8 bits per lane. > > > > > > Based on the number of lanes and the supported data rate, this function > > > reads the device tree property and stores in the presets structure. > > > > > > Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com> > > > --- > > > drivers/pci/of.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ > > > drivers/pci/pci.h | 17 +++++++++++++++-- > > > 2 files changed, 60 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/pci/of.c b/drivers/pci/of.c > > > index dacea3fc5128..99e0e7ae12e9 100644 > > > --- a/drivers/pci/of.c > > > +++ b/drivers/pci/of.c > > > @@ -826,3 +826,48 @@ u32 of_pci_get_slot_power_limit(struct device_node *node, > > > return slot_power_limit_mw; > > > } > > > EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit); > > > + > > > > kerneldoc? Define who should free the memory and how. > > > I will update this in next series. > as we are allocating using devm_kzalloc it should be freed on driver > detach, as no special freeing is required. > > > +int of_pci_get_equalization_presets(struct device *dev, > > > + struct pci_eq_presets *presets, > > > + int num_lanes) > > > +{ > > > + char name[20]; > > > + void **preset; > > > + void *temp; > > > + int ret; > > > + > > > + if (of_property_present(dev->of_node, "eq-presets-8gts")) { > > > + presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * num_lanes, GFP_KERNEL); > > > + if (!presets->eq_presets_8gts) > > > + return -ENOMEM; > > > + > > > + ret = of_property_read_u16_array(dev->of_node, "eq-presets-8gts", > > > + presets->eq_presets_8gts, num_lanes); > > > + if (ret) { > > > + dev_err(dev, "Error reading eq-presets-8gts %d\n", ret); > > > + return ret; > > > + } > > > + } > > > + > > > + for (int i = 1; i < sizeof(struct pci_eq_presets) / sizeof(void *); i++) { > > > + snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); > > > + if (of_property_present(dev->of_node, name)) { > > > + temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, GFP_KERNEL); > > > + if (!temp) > > > + return -ENOMEM; > > > + > > > + ret = of_property_read_u8_array(dev->of_node, name, > > > + temp, num_lanes); > > > + if (ret) { > > > + dev_err(dev, "Error %s %d\n", name, ret); > > > + return ret; > > > + } > > > + > > > + preset = (void **)((u8 *)presets + i * sizeof(void *)); > > > > Ugh. > > > I was trying iterate over each element on the structure as presets holds the > starting address of the structure and to that we are adding size of the void > * point to go to each element. I did this way to reduce the > redundant code to read all the gts which has same way of storing the data > from the device tree. I will add comments here in the next series. Please rewrite this in a cleaner way. The code shouldn't raise questions. > > > + *preset = temp; > > > + } > > > + } > > > + > > > + return 0; > > > +} > > > +EXPORT_SYMBOL_GPL(of_pci_get_equalization_presets); > > > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h > > > index 14d00ce45bfa..82362d58bedc 100644 > > > --- a/drivers/pci/pci.h > > > +++ b/drivers/pci/pci.h > > > @@ -731,7 +731,12 @@ static inline u64 pci_rebar_size_to_bytes(int size) > > > } > > > struct device_node; > > > - > > > +struct pci_eq_presets { > > > + void *eq_presets_8gts; > > > + void *eq_presets_16gts; > > > + void *eq_presets_32gts; > > > + void *eq_presets_64gts; > > > > Why are all of those void*? 8gts is u16*, all other are u8*. > > > To have common parsing logic I moved them to void*, as these are pointers > actual memory is allocated by of_pci_get_equalization_presets() > based upon the gts these should not give any issues. Please, don't. They have types. void pointers are for the opaque data. > > > +}; > > > > Empty lines before and after the struct definition. > > > ack. > > - Krishna Chaitanya. > > > #ifdef CONFIG_OF > > > int of_pci_parse_bus_range(struct device_node *node, struct resource *res); > > > int of_get_pci_domain_nr(struct device_node *node); > > > @@ -746,7 +751,9 @@ void pci_set_bus_of_node(struct pci_bus *bus); > > > void pci_release_bus_of_node(struct pci_bus *bus); > > > int devm_of_pci_bridge_init(struct device *dev, struct pci_host_bridge *bridge); > > > - > > > +int of_pci_get_equalization_presets(struct device *dev, > > > + struct pci_eq_presets *presets, > > > + int num_lanes); > > > > Keep the empty line. > > > > > #else > > > static inline int > > > of_pci_parse_bus_range(struct device_node *node, struct resource *res) > > > @@ -793,6 +800,12 @@ static inline int devm_of_pci_bridge_init(struct device *dev, struct pci_host_br > > > return 0; > > > } > > > +static inline int of_pci_get_equalization_presets(struct device *dev, > > > + struct pci_eq_presets *presets, > > > + int num_lanes) > > > +{ > > > + return 0; > > > +} > > > #endif /* CONFIG_OF */ > > > struct of_changeset; > > > > > > -- > > > 2.34.1 > > > > >
On Mon, Dec 23, 2024 at 10:13:29PM +0530, Krishna Chaitanya Chundru wrote: > > > On 12/23/2024 8:56 PM, Dmitry Baryshkov wrote: > > On Mon, Dec 23, 2024 at 08:02:23PM +0530, Krishna Chaitanya Chundru wrote: > > > > > > > > > On 12/23/2024 5:17 PM, Dmitry Baryshkov wrote: > > > > On Mon, Dec 23, 2024 at 12:21:15PM +0530, Krishna Chaitanya Chundru wrote: > > > > > PCIe equalization presets are predefined settings used to optimize > > > > > signal integrity by compensating for signal loss and distortion in > > > > > high-speed data transmission. > > > > > > > > > > As per PCIe spec 6.0.1 revision section 8.3.3.3 & 4.2.4 for data rates > > > > > of 8.0 GT/s, 16.0 GT/s, 32.0 GT/s, and 64.0 GT/s, there is a way to > > > > > configure lane equalization presets for each lane to enhance the PCIe > > > > > link reliability. Each preset value represents a different combination > > > > > of pre-shoot and de-emphasis values. For each data rate, different > > > > > registers are defined: for 8.0 GT/s, registers are defined in section > > > > > 7.7.3.4; for 16.0 GT/s, in section 7.7.5.9, etc. The 8.0 GT/s rate has > > > > > an extra receiver preset hint, requiring 16 bits per lane, while the > > > > > remaining data rates use 8 bits per lane. > > > > > > > > > > Based on the number of lanes and the supported data rate, this function > > > > > reads the device tree property and stores in the presets structure. > > > > > > > > > > Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com> > > > > > --- > > > > > drivers/pci/of.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ > > > > > drivers/pci/pci.h | 17 +++++++++++++++-- > > > > > 2 files changed, 60 insertions(+), 2 deletions(-) > > > > > > > > > > diff --git a/drivers/pci/of.c b/drivers/pci/of.c > > > > > index dacea3fc5128..99e0e7ae12e9 100644 > > > > > --- a/drivers/pci/of.c > > > > > +++ b/drivers/pci/of.c > > > > > @@ -826,3 +826,48 @@ u32 of_pci_get_slot_power_limit(struct device_node *node, > > > > > return slot_power_limit_mw; > > > > > } > > > > > EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit); > > > > > + > > > > > > > > kerneldoc? Define who should free the memory and how. > > > > > > > I will update this in next series. > > > as we are allocating using devm_kzalloc it should be freed on driver > > > detach, as no special freeing is required. > > > > > +int of_pci_get_equalization_presets(struct device *dev, > > > > > + struct pci_eq_presets *presets, > > > > > + int num_lanes) > > > > > +{ > > > > > + char name[20]; > > > > > + void **preset; > > > > > + void *temp; > > > > > + int ret; > > > > > + > > > > > + if (of_property_present(dev->of_node, "eq-presets-8gts")) { > > > > > + presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * num_lanes, GFP_KERNEL); > > > > > + if (!presets->eq_presets_8gts) > > > > > + return -ENOMEM; > > > > > + > > > > > + ret = of_property_read_u16_array(dev->of_node, "eq-presets-8gts", > > > > > + presets->eq_presets_8gts, num_lanes); > > > > > + if (ret) { > > > > > + dev_err(dev, "Error reading eq-presets-8gts %d\n", ret); > > > > > + return ret; > > > > > + } > > > > > + } > > > > > + > > > > > + for (int i = 1; i < sizeof(struct pci_eq_presets) / sizeof(void *); i++) { > > > > > + snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); > > > > > + if (of_property_present(dev->of_node, name)) { > > > > > + temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, GFP_KERNEL); > > > > > + if (!temp) > > > > > + return -ENOMEM; > > > > > + > > > > > + ret = of_property_read_u8_array(dev->of_node, name, > > > > > + temp, num_lanes); > > > > > + if (ret) { > > > > > + dev_err(dev, "Error %s %d\n", name, ret); > > > > > + return ret; > > > > > + } > > > > > + > > > > > + preset = (void **)((u8 *)presets + i * sizeof(void *)); > > > > > > > > Ugh. > > > > > > > I was trying iterate over each element on the structure as presets holds the > > > starting address of the structure and to that we are adding size of the void > > > * point to go to each element. I did this way to reduce the > > > redundant code to read all the gts which has same way of storing the data > > > from the device tree. I will add comments here in the next series. > > > > Please rewrite this in a cleaner way. The code shouldn't raise > > questions. > > > > > > > + *preset = temp; > > > > > + } > > > > > + } > > > > > + > > > > > + return 0; > > > > > +} > > > > > +EXPORT_SYMBOL_GPL(of_pci_get_equalization_presets); > > > > > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h > > > > > index 14d00ce45bfa..82362d58bedc 100644 > > > > > --- a/drivers/pci/pci.h > > > > > +++ b/drivers/pci/pci.h > > > > > @@ -731,7 +731,12 @@ static inline u64 pci_rebar_size_to_bytes(int size) > > > > > } > > > > > struct device_node; > > > > > - > > > > > +struct pci_eq_presets { > > > > > + void *eq_presets_8gts; > > > > > + void *eq_presets_16gts; > > > > > + void *eq_presets_32gts; > > > > > + void *eq_presets_64gts; > > > > > > > > Why are all of those void*? 8gts is u16*, all other are u8*. > > > > > > > To have common parsing logic I moved them to void*, as these are pointers > > > actual memory is allocated by of_pci_get_equalization_presets() > > > based upon the gts these should not give any issues. > > > > Please, don't. They have types. void pointers are for the opaque data. > > > ok. > > I think then better to use v1 patch > https://lore.kernel.org/all/20241116-presets-v1-2-878a837a4fee@quicinc.com/ > > konrad, any objection on using v1 as that will be cleaner way even if we > have some repetitive code. Konrad had a nice suggestion about using the array of values. Please use such an array for 16gts and above. This removes most of repetitive code.
On 12/24/2024 12:00 AM, Dmitry Baryshkov wrote: > On Mon, Dec 23, 2024 at 10:13:29PM +0530, Krishna Chaitanya Chundru wrote: >> >> >> On 12/23/2024 8:56 PM, Dmitry Baryshkov wrote: >>> On Mon, Dec 23, 2024 at 08:02:23PM +0530, Krishna Chaitanya Chundru wrote: >>>> >>>> >>>> On 12/23/2024 5:17 PM, Dmitry Baryshkov wrote: >>>>> On Mon, Dec 23, 2024 at 12:21:15PM +0530, Krishna Chaitanya Chundru wrote: >>>>>> PCIe equalization presets are predefined settings used to optimize >>>>>> signal integrity by compensating for signal loss and distortion in >>>>>> high-speed data transmission. >>>>>> >>>>>> As per PCIe spec 6.0.1 revision section 8.3.3.3 & 4.2.4 for data rates >>>>>> of 8.0 GT/s, 16.0 GT/s, 32.0 GT/s, and 64.0 GT/s, there is a way to >>>>>> configure lane equalization presets for each lane to enhance the PCIe >>>>>> link reliability. Each preset value represents a different combination >>>>>> of pre-shoot and de-emphasis values. For each data rate, different >>>>>> registers are defined: for 8.0 GT/s, registers are defined in section >>>>>> 7.7.3.4; for 16.0 GT/s, in section 7.7.5.9, etc. The 8.0 GT/s rate has >>>>>> an extra receiver preset hint, requiring 16 bits per lane, while the >>>>>> remaining data rates use 8 bits per lane. >>>>>> >>>>>> Based on the number of lanes and the supported data rate, this function >>>>>> reads the device tree property and stores in the presets structure. >>>>>> >>>>>> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com> >>>>>> --- >>>>>> drivers/pci/of.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ >>>>>> drivers/pci/pci.h | 17 +++++++++++++++-- >>>>>> 2 files changed, 60 insertions(+), 2 deletions(-) >>>>>> >>>>>> diff --git a/drivers/pci/of.c b/drivers/pci/of.c >>>>>> index dacea3fc5128..99e0e7ae12e9 100644 >>>>>> --- a/drivers/pci/of.c >>>>>> +++ b/drivers/pci/of.c >>>>>> @@ -826,3 +826,48 @@ u32 of_pci_get_slot_power_limit(struct device_node *node, >>>>>> return slot_power_limit_mw; >>>>>> } >>>>>> EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit); >>>>>> + >>>>> >>>>> kerneldoc? Define who should free the memory and how. >>>>> >>>> I will update this in next series. >>>> as we are allocating using devm_kzalloc it should be freed on driver >>>> detach, as no special freeing is required. >>>>>> +int of_pci_get_equalization_presets(struct device *dev, >>>>>> + struct pci_eq_presets *presets, >>>>>> + int num_lanes) >>>>>> +{ >>>>>> + char name[20]; >>>>>> + void **preset; >>>>>> + void *temp; >>>>>> + int ret; >>>>>> + >>>>>> + if (of_property_present(dev->of_node, "eq-presets-8gts")) { >>>>>> + presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * num_lanes, GFP_KERNEL); >>>>>> + if (!presets->eq_presets_8gts) >>>>>> + return -ENOMEM; >>>>>> + >>>>>> + ret = of_property_read_u16_array(dev->of_node, "eq-presets-8gts", >>>>>> + presets->eq_presets_8gts, num_lanes); >>>>>> + if (ret) { >>>>>> + dev_err(dev, "Error reading eq-presets-8gts %d\n", ret); >>>>>> + return ret; >>>>>> + } >>>>>> + } >>>>>> + >>>>>> + for (int i = 1; i < sizeof(struct pci_eq_presets) / sizeof(void *); i++) { >>>>>> + snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); >>>>>> + if (of_property_present(dev->of_node, name)) { >>>>>> + temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, GFP_KERNEL); >>>>>> + if (!temp) >>>>>> + return -ENOMEM; >>>>>> + >>>>>> + ret = of_property_read_u8_array(dev->of_node, name, >>>>>> + temp, num_lanes); >>>>>> + if (ret) { >>>>>> + dev_err(dev, "Error %s %d\n", name, ret); >>>>>> + return ret; >>>>>> + } >>>>>> + >>>>>> + preset = (void **)((u8 *)presets + i * sizeof(void *)); >>>>> >>>>> Ugh. >>>>> >>>> I was trying iterate over each element on the structure as presets holds the >>>> starting address of the structure and to that we are adding size of the void >>>> * point to go to each element. I did this way to reduce the >>>> redundant code to read all the gts which has same way of storing the data >>>> from the device tree. I will add comments here in the next series. >>> >>> Please rewrite this in a cleaner way. The code shouldn't raise >>> questions. >>> >>>>>> + *preset = temp; >>>>>> + } >>>>>> + } >>>>>> + >>>>>> + return 0; >>>>>> +} >>>>>> +EXPORT_SYMBOL_GPL(of_pci_get_equalization_presets); >>>>>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h >>>>>> index 14d00ce45bfa..82362d58bedc 100644 >>>>>> --- a/drivers/pci/pci.h >>>>>> +++ b/drivers/pci/pci.h >>>>>> @@ -731,7 +731,12 @@ static inline u64 pci_rebar_size_to_bytes(int size) >>>>>> } >>>>>> struct device_node; >>>>>> - >>>>>> +struct pci_eq_presets { >>>>>> + void *eq_presets_8gts; >>>>>> + void *eq_presets_16gts; >>>>>> + void *eq_presets_32gts; >>>>>> + void *eq_presets_64gts; >>>>> >>>>> Why are all of those void*? 8gts is u16*, all other are u8*. >>>>> >>>> To have common parsing logic I moved them to void*, as these are pointers >>>> actual memory is allocated by of_pci_get_equalization_presets() >>>> based upon the gts these should not give any issues. >>> >>> Please, don't. They have types. void pointers are for the opaque data. >>> >> ok. >> >> I think then better to use v1 patch >> https://lore.kernel.org/all/20241116-presets-v1-2-878a837a4fee@quicinc.com/ >> >> konrad, any objection on using v1 as that will be cleaner way even if we >> have some repetitive code. > > Konrad had a nice suggestion about using the array of values. Please use > such an array for 16gts and above. This removes most of repetitive code. > I don't feel having array in the preset structure looks good, I have come up with this logic if you feel it is not so good I will go to the suggested way by having array for 16gts and above. if (of_property_present(dev->of_node, "eq-presets-8gts")) { presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * num_lanes, GFP_KERNEL); if (!presets->eq_presets_8gts) return -ENOMEM; ret = of_property_read_u16_array(dev->of_node, "eq-presets-8gts", presets->eq_presets_8gts, num_lanes); if (ret) { dev_err(dev, "Error reading eq-presets-8gts %d\n", ret); return ret; } } for (int i = EQ_PRESET_TYPE_16GTS; i < EQ_PRESET_TYPE_64GTS; i++) { snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); if (of_property_present(dev->of_node, name)) { temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, GFP_KERNEL); if (!temp) return -ENOMEM; ret = of_property_read_u8_array(dev->of_node, name, temp, num_lanes); if (ret) { dev_err(dev, "Error %s %d\n", name, ret); return ret; } switch (i) { case EQ_PRESET_TYPE_16GTS: presets->eq_presets_16gts = temp; break; case EQ_PRESET_TYPE_32GTS: presets->eq_presets_32gts = temp; break; case EQ_PRESET_TYPE_64GTS: presets->eq_presets_64gts = temp; break; } } } - Krishna Chaitanya. >
On Tue, Dec 24, 2024 at 02:47:00PM +0530, Krishna Chaitanya Chundru wrote: > > > On 12/24/2024 12:00 AM, Dmitry Baryshkov wrote: > > On Mon, Dec 23, 2024 at 10:13:29PM +0530, Krishna Chaitanya Chundru wrote: > > > > > > > > > On 12/23/2024 8:56 PM, Dmitry Baryshkov wrote: > > > > On Mon, Dec 23, 2024 at 08:02:23PM +0530, Krishna Chaitanya Chundru wrote: > > > > > > > > > > > > > > > On 12/23/2024 5:17 PM, Dmitry Baryshkov wrote: > > > > > > On Mon, Dec 23, 2024 at 12:21:15PM +0530, Krishna Chaitanya Chundru wrote: > > > > > > > PCIe equalization presets are predefined settings used to optimize > > > > > > > signal integrity by compensating for signal loss and distortion in > > > > > > > high-speed data transmission. > > > > > > > > > > > > > > As per PCIe spec 6.0.1 revision section 8.3.3.3 & 4.2.4 for data rates > > > > > > > of 8.0 GT/s, 16.0 GT/s, 32.0 GT/s, and 64.0 GT/s, there is a way to > > > > > > > configure lane equalization presets for each lane to enhance the PCIe > > > > > > > link reliability. Each preset value represents a different combination > > > > > > > of pre-shoot and de-emphasis values. For each data rate, different > > > > > > > registers are defined: for 8.0 GT/s, registers are defined in section > > > > > > > 7.7.3.4; for 16.0 GT/s, in section 7.7.5.9, etc. The 8.0 GT/s rate has > > > > > > > an extra receiver preset hint, requiring 16 bits per lane, while the > > > > > > > remaining data rates use 8 bits per lane. > > > > > > > > > > > > > > Based on the number of lanes and the supported data rate, this function > > > > > > > reads the device tree property and stores in the presets structure. > > > > > > > > > > > > > > Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com> > > > > > > > --- > > > > > > > drivers/pci/of.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ > > > > > > > drivers/pci/pci.h | 17 +++++++++++++++-- > > > > > > > 2 files changed, 60 insertions(+), 2 deletions(-) > > > > > > > > > > > > > > diff --git a/drivers/pci/of.c b/drivers/pci/of.c > > > > > > > index dacea3fc5128..99e0e7ae12e9 100644 > > > > > > > --- a/drivers/pci/of.c > > > > > > > +++ b/drivers/pci/of.c > > > > > > > @@ -826,3 +826,48 @@ u32 of_pci_get_slot_power_limit(struct device_node *node, > > > > > > > return slot_power_limit_mw; > > > > > > > } > > > > > > > EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit); > > > > > > > + > > > > > > > > > > > > kerneldoc? Define who should free the memory and how. > > > > > > > > > > > I will update this in next series. > > > > > as we are allocating using devm_kzalloc it should be freed on driver > > > > > detach, as no special freeing is required. > > > > > > > +int of_pci_get_equalization_presets(struct device *dev, > > > > > > > + struct pci_eq_presets *presets, > > > > > > > + int num_lanes) > > > > > > > +{ > > > > > > > + char name[20]; > > > > > > > + void **preset; > > > > > > > + void *temp; > > > > > > > + int ret; > > > > > > > + > > > > > > > + if (of_property_present(dev->of_node, "eq-presets-8gts")) { > > > > > > > + presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * num_lanes, GFP_KERNEL); > > > > > > > + if (!presets->eq_presets_8gts) > > > > > > > + return -ENOMEM; > > > > > > > + > > > > > > > + ret = of_property_read_u16_array(dev->of_node, "eq-presets-8gts", > > > > > > > + presets->eq_presets_8gts, num_lanes); > > > > > > > + if (ret) { > > > > > > > + dev_err(dev, "Error reading eq-presets-8gts %d\n", ret); > > > > > > > + return ret; > > > > > > > + } > > > > > > > + } > > > > > > > + > > > > > > > + for (int i = 1; i < sizeof(struct pci_eq_presets) / sizeof(void *); i++) { > > > > > > > + snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); > > > > > > > + if (of_property_present(dev->of_node, name)) { > > > > > > > + temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, GFP_KERNEL); > > > > > > > + if (!temp) > > > > > > > + return -ENOMEM; > > > > > > > + > > > > > > > + ret = of_property_read_u8_array(dev->of_node, name, > > > > > > > + temp, num_lanes); > > > > > > > + if (ret) { > > > > > > > + dev_err(dev, "Error %s %d\n", name, ret); > > > > > > > + return ret; > > > > > > > + } > > > > > > > + > > > > > > > + preset = (void **)((u8 *)presets + i * sizeof(void *)); > > > > > > > > > > > > Ugh. > > > > > > > > > > > I was trying iterate over each element on the structure as presets holds the > > > > > starting address of the structure and to that we are adding size of the void > > > > > * point to go to each element. I did this way to reduce the > > > > > redundant code to read all the gts which has same way of storing the data > > > > > from the device tree. I will add comments here in the next series. > > > > > > > > Please rewrite this in a cleaner way. The code shouldn't raise > > > > questions. > > > > > > > > > > > + *preset = temp; > > > > > > > + } > > > > > > > + } > > > > > > > + > > > > > > > + return 0; > > > > > > > +} > > > > > > > +EXPORT_SYMBOL_GPL(of_pci_get_equalization_presets); > > > > > > > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h > > > > > > > index 14d00ce45bfa..82362d58bedc 100644 > > > > > > > --- a/drivers/pci/pci.h > > > > > > > +++ b/drivers/pci/pci.h > > > > > > > @@ -731,7 +731,12 @@ static inline u64 pci_rebar_size_to_bytes(int size) > > > > > > > } > > > > > > > struct device_node; > > > > > > > - > > > > > > > +struct pci_eq_presets { > > > > > > > + void *eq_presets_8gts; > > > > > > > + void *eq_presets_16gts; > > > > > > > + void *eq_presets_32gts; > > > > > > > + void *eq_presets_64gts; > > > > > > > > > > > > Why are all of those void*? 8gts is u16*, all other are u8*. > > > > > > > > > > > To have common parsing logic I moved them to void*, as these are pointers > > > > > actual memory is allocated by of_pci_get_equalization_presets() > > > > > based upon the gts these should not give any issues. > > > > > > > > Please, don't. They have types. void pointers are for the opaque data. > > > > > > > ok. > > > > > > I think then better to use v1 patch > > > https://lore.kernel.org/all/20241116-presets-v1-2-878a837a4fee@quicinc.com/ > > > > > > konrad, any objection on using v1 as that will be cleaner way even if we > > > have some repetitive code. > > > > Konrad had a nice suggestion about using the array of values. Please use > > such an array for 16gts and above. This removes most of repetitive code. > > > I don't feel having array in the preset structure looks good, I have > come up with this logic if you feel it is not so good I will go to the > suggested way by having array for 16gts and above. > > if (of_property_present(dev->of_node, "eq-presets-8gts")) { > presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * > num_lanes, GFP_KERNEL); > if (!presets->eq_presets_8gts) > return -ENOMEM; > > ret = of_property_read_u16_array(dev->of_node, > "eq-presets-8gts", > > presets->eq_presets_8gts, num_lanes); > if (ret) { > dev_err(dev, "Error reading eq-presets-8gts %d\n", > ret); > return ret; > } > } > > for (int i = EQ_PRESET_TYPE_16GTS; i < EQ_PRESET_TYPE_64GTS; i++) { > snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); > if (of_property_present(dev->of_node, name)) { > temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, > GFP_KERNEL); > if (!temp) > return -ENOMEM; > > ret = of_property_read_u8_array(dev->of_node, name, > temp, num_lanes); > if (ret) { > dev_err(dev, "Error %s %d\n", name, ret); > return ret; > } > > switch (i) { > case EQ_PRESET_TYPE_16GTS: > presets->eq_presets_16gts = temp; > break; > case EQ_PRESET_TYPE_32GTS: > presets->eq_presets_32gts = temp; > break; > case EQ_PRESET_TYPE_64GTS: > presets->eq_presets_64gts = temp; > break; > } This looks like 'presets->eq_presets[i] = temp;', but I won't insist on that. Also, a strange thought came to my mind: we know that there won't be more than 16 lanes. Can we have the following structure instead: #define MAX_LANES 16 enum pcie_gts { PCIE_GTS_16GTS, PCIE_GTS_32GTS, PCIE_GTS_64GTS, PCIE_GTS_MAX, }; struct pci_eq_presets { u16 eq_presets_8gts[MAX_LANES]; u8 eq_presets_Ngts[PCIE_GTS_MAX][MAX_LANES]; }; This should allow you to drop the of_property_present() and devm_kzalloc(). Just read DT data into a corresponding array. > } > } > - Krishna Chaitanya. > > >
On 12/24/2024 3:25 PM, Dmitry Baryshkov wrote: > On Tue, Dec 24, 2024 at 02:47:00PM +0530, Krishna Chaitanya Chundru wrote: >> >> >> On 12/24/2024 12:00 AM, Dmitry Baryshkov wrote: >>> On Mon, Dec 23, 2024 at 10:13:29PM +0530, Krishna Chaitanya Chundru wrote: >>>> >>>> >>>> On 12/23/2024 8:56 PM, Dmitry Baryshkov wrote: >>>>> On Mon, Dec 23, 2024 at 08:02:23PM +0530, Krishna Chaitanya Chundru wrote: >>>>>> >>>>>> >>>>>> On 12/23/2024 5:17 PM, Dmitry Baryshkov wrote: >>>>>>> On Mon, Dec 23, 2024 at 12:21:15PM +0530, Krishna Chaitanya Chundru wrote: >>>>>>>> PCIe equalization presets are predefined settings used to optimize >>>>>>>> signal integrity by compensating for signal loss and distortion in >>>>>>>> high-speed data transmission. >>>>>>>> >>>>>>>> As per PCIe spec 6.0.1 revision section 8.3.3.3 & 4.2.4 for data rates >>>>>>>> of 8.0 GT/s, 16.0 GT/s, 32.0 GT/s, and 64.0 GT/s, there is a way to >>>>>>>> configure lane equalization presets for each lane to enhance the PCIe >>>>>>>> link reliability. Each preset value represents a different combination >>>>>>>> of pre-shoot and de-emphasis values. For each data rate, different >>>>>>>> registers are defined: for 8.0 GT/s, registers are defined in section >>>>>>>> 7.7.3.4; for 16.0 GT/s, in section 7.7.5.9, etc. The 8.0 GT/s rate has >>>>>>>> an extra receiver preset hint, requiring 16 bits per lane, while the >>>>>>>> remaining data rates use 8 bits per lane. >>>>>>>> >>>>>>>> Based on the number of lanes and the supported data rate, this function >>>>>>>> reads the device tree property and stores in the presets structure. >>>>>>>> >>>>>>>> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com> >>>>>>>> --- >>>>>>>> drivers/pci/of.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ >>>>>>>> drivers/pci/pci.h | 17 +++++++++++++++-- >>>>>>>> 2 files changed, 60 insertions(+), 2 deletions(-) >>>>>>>> >>>>>>>> diff --git a/drivers/pci/of.c b/drivers/pci/of.c >>>>>>>> index dacea3fc5128..99e0e7ae12e9 100644 >>>>>>>> --- a/drivers/pci/of.c >>>>>>>> +++ b/drivers/pci/of.c >>>>>>>> @@ -826,3 +826,48 @@ u32 of_pci_get_slot_power_limit(struct device_node *node, >>>>>>>> return slot_power_limit_mw; >>>>>>>> } >>>>>>>> EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit); >>>>>>>> + >>>>>>> >>>>>>> kerneldoc? Define who should free the memory and how. >>>>>>> >>>>>> I will update this in next series. >>>>>> as we are allocating using devm_kzalloc it should be freed on driver >>>>>> detach, as no special freeing is required. >>>>>>>> +int of_pci_get_equalization_presets(struct device *dev, >>>>>>>> + struct pci_eq_presets *presets, >>>>>>>> + int num_lanes) >>>>>>>> +{ >>>>>>>> + char name[20]; >>>>>>>> + void **preset; >>>>>>>> + void *temp; >>>>>>>> + int ret; >>>>>>>> + >>>>>>>> + if (of_property_present(dev->of_node, "eq-presets-8gts")) { >>>>>>>> + presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * num_lanes, GFP_KERNEL); >>>>>>>> + if (!presets->eq_presets_8gts) >>>>>>>> + return -ENOMEM; >>>>>>>> + >>>>>>>> + ret = of_property_read_u16_array(dev->of_node, "eq-presets-8gts", >>>>>>>> + presets->eq_presets_8gts, num_lanes); >>>>>>>> + if (ret) { >>>>>>>> + dev_err(dev, "Error reading eq-presets-8gts %d\n", ret); >>>>>>>> + return ret; >>>>>>>> + } >>>>>>>> + } >>>>>>>> + >>>>>>>> + for (int i = 1; i < sizeof(struct pci_eq_presets) / sizeof(void *); i++) { >>>>>>>> + snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); >>>>>>>> + if (of_property_present(dev->of_node, name)) { >>>>>>>> + temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, GFP_KERNEL); >>>>>>>> + if (!temp) >>>>>>>> + return -ENOMEM; >>>>>>>> + >>>>>>>> + ret = of_property_read_u8_array(dev->of_node, name, >>>>>>>> + temp, num_lanes); >>>>>>>> + if (ret) { >>>>>>>> + dev_err(dev, "Error %s %d\n", name, ret); >>>>>>>> + return ret; >>>>>>>> + } >>>>>>>> + >>>>>>>> + preset = (void **)((u8 *)presets + i * sizeof(void *)); >>>>>>> >>>>>>> Ugh. >>>>>>> >>>>>> I was trying iterate over each element on the structure as presets holds the >>>>>> starting address of the structure and to that we are adding size of the void >>>>>> * point to go to each element. I did this way to reduce the >>>>>> redundant code to read all the gts which has same way of storing the data >>>>>> from the device tree. I will add comments here in the next series. >>>>> >>>>> Please rewrite this in a cleaner way. The code shouldn't raise >>>>> questions. >>>>> >>>>>>>> + *preset = temp; >>>>>>>> + } >>>>>>>> + } >>>>>>>> + >>>>>>>> + return 0; >>>>>>>> +} >>>>>>>> +EXPORT_SYMBOL_GPL(of_pci_get_equalization_presets); >>>>>>>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h >>>>>>>> index 14d00ce45bfa..82362d58bedc 100644 >>>>>>>> --- a/drivers/pci/pci.h >>>>>>>> +++ b/drivers/pci/pci.h >>>>>>>> @@ -731,7 +731,12 @@ static inline u64 pci_rebar_size_to_bytes(int size) >>>>>>>> } >>>>>>>> struct device_node; >>>>>>>> - >>>>>>>> +struct pci_eq_presets { >>>>>>>> + void *eq_presets_8gts; >>>>>>>> + void *eq_presets_16gts; >>>>>>>> + void *eq_presets_32gts; >>>>>>>> + void *eq_presets_64gts; >>>>>>> >>>>>>> Why are all of those void*? 8gts is u16*, all other are u8*. >>>>>>> >>>>>> To have common parsing logic I moved them to void*, as these are pointers >>>>>> actual memory is allocated by of_pci_get_equalization_presets() >>>>>> based upon the gts these should not give any issues. >>>>> >>>>> Please, don't. They have types. void pointers are for the opaque data. >>>>> >>>> ok. >>>> >>>> I think then better to use v1 patch >>>> https://lore.kernel.org/all/20241116-presets-v1-2-878a837a4fee@quicinc.com/ >>>> >>>> konrad, any objection on using v1 as that will be cleaner way even if we >>>> have some repetitive code. >>> >>> Konrad had a nice suggestion about using the array of values. Please use >>> such an array for 16gts and above. This removes most of repetitive code. >>> >> I don't feel having array in the preset structure looks good, I have >> come up with this logic if you feel it is not so good I will go to the >> suggested way by having array for 16gts and above. >> >> if (of_property_present(dev->of_node, "eq-presets-8gts")) { >> presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * >> num_lanes, GFP_KERNEL); >> if (!presets->eq_presets_8gts) >> return -ENOMEM; >> >> ret = of_property_read_u16_array(dev->of_node, >> "eq-presets-8gts", >> >> presets->eq_presets_8gts, num_lanes); >> if (ret) { >> dev_err(dev, "Error reading eq-presets-8gts %d\n", >> ret); >> return ret; >> } >> } >> >> for (int i = EQ_PRESET_TYPE_16GTS; i < EQ_PRESET_TYPE_64GTS; i++) { >> snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); >> if (of_property_present(dev->of_node, name)) { >> temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, >> GFP_KERNEL); >> if (!temp) >> return -ENOMEM; >> >> ret = of_property_read_u8_array(dev->of_node, name, >> temp, num_lanes); >> if (ret) { >> dev_err(dev, "Error %s %d\n", name, ret); >> return ret; >> } >> >> switch (i) { >> case EQ_PRESET_TYPE_16GTS: >> presets->eq_presets_16gts = temp; >> break; >> case EQ_PRESET_TYPE_32GTS: >> presets->eq_presets_32gts = temp; >> break; >> case EQ_PRESET_TYPE_64GTS: >> presets->eq_presets_64gts = temp; >> break; >> } > > This looks like 'presets->eq_presets[i] = temp;', but I won't insist on > that. > > Also, a strange thought came to my mind: we know that there won't be > more than 16 lanes. Can we have the following structure instead: > > #define MAX_LANES 16 > enum pcie_gts { > PCIE_GTS_16GTS, > PCIE_GTS_32GTS, > PCIE_GTS_64GTS, > PCIE_GTS_MAX, > }; > struct pci_eq_presets { > u16 eq_presets_8gts[MAX_LANES]; > u8 eq_presets_Ngts[PCIE_GTS_MAX][MAX_LANES]; > }; > > This should allow you to drop the of_property_present() and > devm_kzalloc(). Just read DT data into a corresponding array. > in the dwc driver patch I was using pointers and memory allocation to known if the property is present or not. If I use this way I might end up reading dt property again. I think better to switch to have a array for above 16gts. - Krishna Chaitanya. >> } >> } >> - Krishna Chaitanya. >> >>> >
On Tue, 24 Dec 2024 at 12:36, Krishna Chaitanya Chundru <quic_krichai@quicinc.com> wrote: > > > > On 12/24/2024 3:25 PM, Dmitry Baryshkov wrote: > > On Tue, Dec 24, 2024 at 02:47:00PM +0530, Krishna Chaitanya Chundru wrote: > >> > >> > >> On 12/24/2024 12:00 AM, Dmitry Baryshkov wrote: > >>> On Mon, Dec 23, 2024 at 10:13:29PM +0530, Krishna Chaitanya Chundru wrote: > >>>> > >>>> > >>>> On 12/23/2024 8:56 PM, Dmitry Baryshkov wrote: > >>>>> On Mon, Dec 23, 2024 at 08:02:23PM +0530, Krishna Chaitanya Chundru wrote: > >>>>>> > >>>>>> > >>>>>> On 12/23/2024 5:17 PM, Dmitry Baryshkov wrote: > >>>>>>> On Mon, Dec 23, 2024 at 12:21:15PM +0530, Krishna Chaitanya Chundru wrote: > >>>>>>>> PCIe equalization presets are predefined settings used to optimize > >>>>>>>> signal integrity by compensating for signal loss and distortion in > >>>>>>>> high-speed data transmission. > >>>>>>>> > >>>>>>>> As per PCIe spec 6.0.1 revision section 8.3.3.3 & 4.2.4 for data rates > >>>>>>>> of 8.0 GT/s, 16.0 GT/s, 32.0 GT/s, and 64.0 GT/s, there is a way to > >>>>>>>> configure lane equalization presets for each lane to enhance the PCIe > >>>>>>>> link reliability. Each preset value represents a different combination > >>>>>>>> of pre-shoot and de-emphasis values. For each data rate, different > >>>>>>>> registers are defined: for 8.0 GT/s, registers are defined in section > >>>>>>>> 7.7.3.4; for 16.0 GT/s, in section 7.7.5.9, etc. The 8.0 GT/s rate has > >>>>>>>> an extra receiver preset hint, requiring 16 bits per lane, while the > >>>>>>>> remaining data rates use 8 bits per lane. > >>>>>>>> > >>>>>>>> Based on the number of lanes and the supported data rate, this function > >>>>>>>> reads the device tree property and stores in the presets structure. > >>>>>>>> > >>>>>>>> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com> > >>>>>>>> --- > >>>>>>>> drivers/pci/of.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ > >>>>>>>> drivers/pci/pci.h | 17 +++++++++++++++-- > >>>>>>>> 2 files changed, 60 insertions(+), 2 deletions(-) > >>>>>>>> > >>>>>>>> diff --git a/drivers/pci/of.c b/drivers/pci/of.c > >>>>>>>> index dacea3fc5128..99e0e7ae12e9 100644 > >>>>>>>> --- a/drivers/pci/of.c > >>>>>>>> +++ b/drivers/pci/of.c > >>>>>>>> @@ -826,3 +826,48 @@ u32 of_pci_get_slot_power_limit(struct device_node *node, > >>>>>>>> return slot_power_limit_mw; > >>>>>>>> } > >>>>>>>> EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit); > >>>>>>>> + > >>>>>>> > >>>>>>> kerneldoc? Define who should free the memory and how. > >>>>>>> > >>>>>> I will update this in next series. > >>>>>> as we are allocating using devm_kzalloc it should be freed on driver > >>>>>> detach, as no special freeing is required. > >>>>>>>> +int of_pci_get_equalization_presets(struct device *dev, > >>>>>>>> + struct pci_eq_presets *presets, > >>>>>>>> + int num_lanes) > >>>>>>>> +{ > >>>>>>>> + char name[20]; > >>>>>>>> + void **preset; > >>>>>>>> + void *temp; > >>>>>>>> + int ret; > >>>>>>>> + > >>>>>>>> + if (of_property_present(dev->of_node, "eq-presets-8gts")) { > >>>>>>>> + presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * num_lanes, GFP_KERNEL); > >>>>>>>> + if (!presets->eq_presets_8gts) > >>>>>>>> + return -ENOMEM; > >>>>>>>> + > >>>>>>>> + ret = of_property_read_u16_array(dev->of_node, "eq-presets-8gts", > >>>>>>>> + presets->eq_presets_8gts, num_lanes); > >>>>>>>> + if (ret) { > >>>>>>>> + dev_err(dev, "Error reading eq-presets-8gts %d\n", ret); > >>>>>>>> + return ret; > >>>>>>>> + } > >>>>>>>> + } > >>>>>>>> + > >>>>>>>> + for (int i = 1; i < sizeof(struct pci_eq_presets) / sizeof(void *); i++) { > >>>>>>>> + snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); > >>>>>>>> + if (of_property_present(dev->of_node, name)) { > >>>>>>>> + temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, GFP_KERNEL); > >>>>>>>> + if (!temp) > >>>>>>>> + return -ENOMEM; > >>>>>>>> + > >>>>>>>> + ret = of_property_read_u8_array(dev->of_node, name, > >>>>>>>> + temp, num_lanes); > >>>>>>>> + if (ret) { > >>>>>>>> + dev_err(dev, "Error %s %d\n", name, ret); > >>>>>>>> + return ret; > >>>>>>>> + } > >>>>>>>> + > >>>>>>>> + preset = (void **)((u8 *)presets + i * sizeof(void *)); > >>>>>>> > >>>>>>> Ugh. > >>>>>>> > >>>>>> I was trying iterate over each element on the structure as presets holds the > >>>>>> starting address of the structure and to that we are adding size of the void > >>>>>> * point to go to each element. I did this way to reduce the > >>>>>> redundant code to read all the gts which has same way of storing the data > >>>>>> from the device tree. I will add comments here in the next series. > >>>>> > >>>>> Please rewrite this in a cleaner way. The code shouldn't raise > >>>>> questions. > >>>>> > >>>>>>>> + *preset = temp; > >>>>>>>> + } > >>>>>>>> + } > >>>>>>>> + > >>>>>>>> + return 0; > >>>>>>>> +} > >>>>>>>> +EXPORT_SYMBOL_GPL(of_pci_get_equalization_presets); > >>>>>>>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h > >>>>>>>> index 14d00ce45bfa..82362d58bedc 100644 > >>>>>>>> --- a/drivers/pci/pci.h > >>>>>>>> +++ b/drivers/pci/pci.h > >>>>>>>> @@ -731,7 +731,12 @@ static inline u64 pci_rebar_size_to_bytes(int size) > >>>>>>>> } > >>>>>>>> struct device_node; > >>>>>>>> - > >>>>>>>> +struct pci_eq_presets { > >>>>>>>> + void *eq_presets_8gts; > >>>>>>>> + void *eq_presets_16gts; > >>>>>>>> + void *eq_presets_32gts; > >>>>>>>> + void *eq_presets_64gts; > >>>>>>> > >>>>>>> Why are all of those void*? 8gts is u16*, all other are u8*. > >>>>>>> > >>>>>> To have common parsing logic I moved them to void*, as these are pointers > >>>>>> actual memory is allocated by of_pci_get_equalization_presets() > >>>>>> based upon the gts these should not give any issues. > >>>>> > >>>>> Please, don't. They have types. void pointers are for the opaque data. > >>>>> > >>>> ok. > >>>> > >>>> I think then better to use v1 patch > >>>> https://lore.kernel.org/all/20241116-presets-v1-2-878a837a4fee@quicinc.com/ > >>>> > >>>> konrad, any objection on using v1 as that will be cleaner way even if we > >>>> have some repetitive code. > >>> > >>> Konrad had a nice suggestion about using the array of values. Please use > >>> such an array for 16gts and above. This removes most of repetitive code. > >>> > >> I don't feel having array in the preset structure looks good, I have > >> come up with this logic if you feel it is not so good I will go to the > >> suggested way by having array for 16gts and above. > >> > >> if (of_property_present(dev->of_node, "eq-presets-8gts")) { > >> presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * > >> num_lanes, GFP_KERNEL); > >> if (!presets->eq_presets_8gts) > >> return -ENOMEM; > >> > >> ret = of_property_read_u16_array(dev->of_node, > >> "eq-presets-8gts", > >> > >> presets->eq_presets_8gts, num_lanes); > >> if (ret) { > >> dev_err(dev, "Error reading eq-presets-8gts %d\n", > >> ret); > >> return ret; > >> } > >> } > >> > >> for (int i = EQ_PRESET_TYPE_16GTS; i < EQ_PRESET_TYPE_64GTS; i++) { > >> snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); > >> if (of_property_present(dev->of_node, name)) { > >> temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, > >> GFP_KERNEL); > >> if (!temp) > >> return -ENOMEM; > >> > >> ret = of_property_read_u8_array(dev->of_node, name, > >> temp, num_lanes); > >> if (ret) { > >> dev_err(dev, "Error %s %d\n", name, ret); > >> return ret; > >> } > >> > >> switch (i) { > >> case EQ_PRESET_TYPE_16GTS: > >> presets->eq_presets_16gts = temp; > >> break; > >> case EQ_PRESET_TYPE_32GTS: > >> presets->eq_presets_32gts = temp; > >> break; > >> case EQ_PRESET_TYPE_64GTS: > >> presets->eq_presets_64gts = temp; > >> break; > >> } > > > > This looks like 'presets->eq_presets[i] = temp;', but I won't insist on > > that. > > > > Also, a strange thought came to my mind: we know that there won't be > > more than 16 lanes. Can we have the following structure instead: > > > > #define MAX_LANES 16 > > enum pcie_gts { > > PCIE_GTS_16GTS, > > PCIE_GTS_32GTS, > > PCIE_GTS_64GTS, > > PCIE_GTS_MAX, > > }; > > struct pci_eq_presets { > > u16 eq_presets_8gts[MAX_LANES]; > > u8 eq_presets_Ngts[PCIE_GTS_MAX][MAX_LANES]; > > }; > > > > This should allow you to drop the of_property_present() and > > devm_kzalloc(). Just read DT data into a corresponding array. > > > in the dwc driver patch I was using pointers and memory allocation > to known if the property is present or not. If I use this way I might > end up reading dt property again. Add foo_valid flags to the struct. > I think better to switch to have a > array for above 16gts. Whichever way works for you. > > - Krishna Chaitanya. > >> } > >> } > >> - Krishna Chaitanya. > >> > >>> > >
On 24.12.2024 11:57 AM, Dmitry Baryshkov wrote: > On Tue, 24 Dec 2024 at 12:36, Krishna Chaitanya Chundru > <quic_krichai@quicinc.com> wrote: >> >> >> >> On 12/24/2024 3:25 PM, Dmitry Baryshkov wrote: >>> On Tue, Dec 24, 2024 at 02:47:00PM +0530, Krishna Chaitanya Chundru wrote: >>>> >>>> >>>> On 12/24/2024 12:00 AM, Dmitry Baryshkov wrote: >>>>> On Mon, Dec 23, 2024 at 10:13:29PM +0530, Krishna Chaitanya Chundru wrote: >>>>>> >>>>>> >>>>>> On 12/23/2024 8:56 PM, Dmitry Baryshkov wrote: >>>>>>> On Mon, Dec 23, 2024 at 08:02:23PM +0530, Krishna Chaitanya Chundru wrote: >>>>>>>> >>>>>>>> >>>>>>>> On 12/23/2024 5:17 PM, Dmitry Baryshkov wrote: >>>>>>>>> On Mon, Dec 23, 2024 at 12:21:15PM +0530, Krishna Chaitanya Chundru wrote: >>>>>>>>>> PCIe equalization presets are predefined settings used to optimize >>>>>>>>>> signal integrity by compensating for signal loss and distortion in >>>>>>>>>> high-speed data transmission. >>>>>>>>>> >>>>>>>>>> As per PCIe spec 6.0.1 revision section 8.3.3.3 & 4.2.4 for data rates >>>>>>>>>> of 8.0 GT/s, 16.0 GT/s, 32.0 GT/s, and 64.0 GT/s, there is a way to >>>>>>>>>> configure lane equalization presets for each lane to enhance the PCIe >>>>>>>>>> link reliability. Each preset value represents a different combination >>>>>>>>>> of pre-shoot and de-emphasis values. For each data rate, different >>>>>>>>>> registers are defined: for 8.0 GT/s, registers are defined in section >>>>>>>>>> 7.7.3.4; for 16.0 GT/s, in section 7.7.5.9, etc. The 8.0 GT/s rate has >>>>>>>>>> an extra receiver preset hint, requiring 16 bits per lane, while the >>>>>>>>>> remaining data rates use 8 bits per lane. >>>>>>>>>> >>>>>>>>>> Based on the number of lanes and the supported data rate, this function >>>>>>>>>> reads the device tree property and stores in the presets structure. >>>>>>>>>> >>>>>>>>>> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com> >>>>>>>>>> --- >>>>>>>>>> drivers/pci/of.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ >>>>>>>>>> drivers/pci/pci.h | 17 +++++++++++++++-- >>>>>>>>>> 2 files changed, 60 insertions(+), 2 deletions(-) >>>>>>>>>> >>>>>>>>>> diff --git a/drivers/pci/of.c b/drivers/pci/of.c >>>>>>>>>> index dacea3fc5128..99e0e7ae12e9 100644 >>>>>>>>>> --- a/drivers/pci/of.c >>>>>>>>>> +++ b/drivers/pci/of.c >>>>>>>>>> @@ -826,3 +826,48 @@ u32 of_pci_get_slot_power_limit(struct device_node *node, >>>>>>>>>> return slot_power_limit_mw; >>>>>>>>>> } >>>>>>>>>> EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit); >>>>>>>>>> + >>>>>>>>> >>>>>>>>> kerneldoc? Define who should free the memory and how. >>>>>>>>> >>>>>>>> I will update this in next series. >>>>>>>> as we are allocating using devm_kzalloc it should be freed on driver >>>>>>>> detach, as no special freeing is required. >>>>>>>>>> +int of_pci_get_equalization_presets(struct device *dev, >>>>>>>>>> + struct pci_eq_presets *presets, >>>>>>>>>> + int num_lanes) >>>>>>>>>> +{ >>>>>>>>>> + char name[20]; >>>>>>>>>> + void **preset; >>>>>>>>>> + void *temp; >>>>>>>>>> + int ret; >>>>>>>>>> + >>>>>>>>>> + if (of_property_present(dev->of_node, "eq-presets-8gts")) { >>>>>>>>>> + presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * num_lanes, GFP_KERNEL); >>>>>>>>>> + if (!presets->eq_presets_8gts) >>>>>>>>>> + return -ENOMEM; >>>>>>>>>> + >>>>>>>>>> + ret = of_property_read_u16_array(dev->of_node, "eq-presets-8gts", >>>>>>>>>> + presets->eq_presets_8gts, num_lanes); >>>>>>>>>> + if (ret) { >>>>>>>>>> + dev_err(dev, "Error reading eq-presets-8gts %d\n", ret); >>>>>>>>>> + return ret; >>>>>>>>>> + } >>>>>>>>>> + } >>>>>>>>>> + >>>>>>>>>> + for (int i = 1; i < sizeof(struct pci_eq_presets) / sizeof(void *); i++) { >>>>>>>>>> + snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); >>>>>>>>>> + if (of_property_present(dev->of_node, name)) { >>>>>>>>>> + temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, GFP_KERNEL); >>>>>>>>>> + if (!temp) >>>>>>>>>> + return -ENOMEM; >>>>>>>>>> + >>>>>>>>>> + ret = of_property_read_u8_array(dev->of_node, name, >>>>>>>>>> + temp, num_lanes); >>>>>>>>>> + if (ret) { >>>>>>>>>> + dev_err(dev, "Error %s %d\n", name, ret); >>>>>>>>>> + return ret; >>>>>>>>>> + } >>>>>>>>>> + >>>>>>>>>> + preset = (void **)((u8 *)presets + i * sizeof(void *)); >>>>>>>>> >>>>>>>>> Ugh. >>>>>>>>> >>>>>>>> I was trying iterate over each element on the structure as presets holds the >>>>>>>> starting address of the structure and to that we are adding size of the void >>>>>>>> * point to go to each element. I did this way to reduce the >>>>>>>> redundant code to read all the gts which has same way of storing the data >>>>>>>> from the device tree. I will add comments here in the next series. >>>>>>> >>>>>>> Please rewrite this in a cleaner way. The code shouldn't raise >>>>>>> questions. >>>>>>> >>>>>>>>>> + *preset = temp; >>>>>>>>>> + } >>>>>>>>>> + } >>>>>>>>>> + >>>>>>>>>> + return 0; >>>>>>>>>> +} >>>>>>>>>> +EXPORT_SYMBOL_GPL(of_pci_get_equalization_presets); >>>>>>>>>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h >>>>>>>>>> index 14d00ce45bfa..82362d58bedc 100644 >>>>>>>>>> --- a/drivers/pci/pci.h >>>>>>>>>> +++ b/drivers/pci/pci.h >>>>>>>>>> @@ -731,7 +731,12 @@ static inline u64 pci_rebar_size_to_bytes(int size) >>>>>>>>>> } >>>>>>>>>> struct device_node; >>>>>>>>>> - >>>>>>>>>> +struct pci_eq_presets { >>>>>>>>>> + void *eq_presets_8gts; >>>>>>>>>> + void *eq_presets_16gts; >>>>>>>>>> + void *eq_presets_32gts; >>>>>>>>>> + void *eq_presets_64gts; >>>>>>>>> >>>>>>>>> Why are all of those void*? 8gts is u16*, all other are u8*. >>>>>>>>> >>>>>>>> To have common parsing logic I moved them to void*, as these are pointers >>>>>>>> actual memory is allocated by of_pci_get_equalization_presets() >>>>>>>> based upon the gts these should not give any issues. >>>>>>> >>>>>>> Please, don't. They have types. void pointers are for the opaque data. >>>>>>> >>>>>> ok. >>>>>> >>>>>> I think then better to use v1 patch >>>>>> https://lore.kernel.org/all/20241116-presets-v1-2-878a837a4fee@quicinc.com/ >>>>>> >>>>>> konrad, any objection on using v1 as that will be cleaner way even if we >>>>>> have some repetitive code. >>>>> >>>>> Konrad had a nice suggestion about using the array of values. Please use >>>>> such an array for 16gts and above. This removes most of repetitive code. >>>>> >>>> I don't feel having array in the preset structure looks good, I have >>>> come up with this logic if you feel it is not so good I will go to the >>>> suggested way by having array for 16gts and above. >>>> >>>> if (of_property_present(dev->of_node, "eq-presets-8gts")) { >>>> presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * >>>> num_lanes, GFP_KERNEL); >>>> if (!presets->eq_presets_8gts) >>>> return -ENOMEM; >>>> >>>> ret = of_property_read_u16_array(dev->of_node, >>>> "eq-presets-8gts", >>>> >>>> presets->eq_presets_8gts, num_lanes); >>>> if (ret) { >>>> dev_err(dev, "Error reading eq-presets-8gts %d\n", >>>> ret); >>>> return ret; >>>> } >>>> } >>>> >>>> for (int i = EQ_PRESET_TYPE_16GTS; i < EQ_PRESET_TYPE_64GTS; i++) { >>>> snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); >>>> if (of_property_present(dev->of_node, name)) { >>>> temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, >>>> GFP_KERNEL); >>>> if (!temp) >>>> return -ENOMEM; >>>> >>>> ret = of_property_read_u8_array(dev->of_node, name, >>>> temp, num_lanes); >>>> if (ret) { >>>> dev_err(dev, "Error %s %d\n", name, ret); >>>> return ret; >>>> } >>>> >>>> switch (i) { >>>> case EQ_PRESET_TYPE_16GTS: >>>> presets->eq_presets_16gts = temp; >>>> break; >>>> case EQ_PRESET_TYPE_32GTS: >>>> presets->eq_presets_32gts = temp; >>>> break; >>>> case EQ_PRESET_TYPE_64GTS: >>>> presets->eq_presets_64gts = temp; >>>> break; >>>> } >>> >>> This looks like 'presets->eq_presets[i] = temp;', but I won't insist on >>> that. >>> >>> Also, a strange thought came to my mind: we know that there won't be >>> more than 16 lanes. Can we have the following structure instead: >>> >>> #define MAX_LANES 16 >>> enum pcie_gts { >>> PCIE_GTS_16GTS, >>> PCIE_GTS_32GTS, >>> PCIE_GTS_64GTS, >>> PCIE_GTS_MAX, >>> }; >>> struct pci_eq_presets { >>> u16 eq_presets_8gts[MAX_LANES]; >>> u8 eq_presets_Ngts[PCIE_GTS_MAX][MAX_LANES]; >>> }; >>> >>> This should allow you to drop the of_property_present() and >>> devm_kzalloc(). Just read DT data into a corresponding array. >>> >> in the dwc driver patch I was using pointers and memory allocation >> to known if the property is present or not. If I use this way I might >> end up reading dt property again. > > Add foo_valid flags to the struct. Some(u8)/None would be fitting, but we're not there yet :( Are all 0x00-0xff(ff) values valid for these presets? >> I think better to switch to have a >> array for above 16gts. > > Whichever way works for you. Sorta-answering the earlier email, I have no concerns either Konrad
On 31.12.2024 5:38 AM, Krishna Chaitanya Chundru wrote: > > > On 12/30/2024 7:11 PM, Konrad Dybcio wrote: >> On 24.12.2024 11:57 AM, Dmitry Baryshkov wrote: >>> On Tue, 24 Dec 2024 at 12:36, Krishna Chaitanya Chundru >>> <quic_krichai@quicinc.com> wrote: >>>> >>>> >>>> >>>> On 12/24/2024 3:25 PM, Dmitry Baryshkov wrote: >>>>> On Tue, Dec 24, 2024 at 02:47:00PM +0530, Krishna Chaitanya Chundru wrote: >>>>>> >>>>>> >>>>>> On 12/24/2024 12:00 AM, Dmitry Baryshkov wrote: >>>>>>> On Mon, Dec 23, 2024 at 10:13:29PM +0530, Krishna Chaitanya Chundru wrote: >>>>>>>> >>>>>>>> >>>>>>>> On 12/23/2024 8:56 PM, Dmitry Baryshkov wrote: >>>>>>>>> On Mon, Dec 23, 2024 at 08:02:23PM +0530, Krishna Chaitanya Chundru wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On 12/23/2024 5:17 PM, Dmitry Baryshkov wrote: >>>>>>>>>>> On Mon, Dec 23, 2024 at 12:21:15PM +0530, Krishna Chaitanya Chundru wrote: >>>>>>>>>>>> PCIe equalization presets are predefined settings used to optimize >>>>>>>>>>>> signal integrity by compensating for signal loss and distortion in >>>>>>>>>>>> high-speed data transmission. >>>>>>>>>>>> >>>>>>>>>>>> As per PCIe spec 6.0.1 revision section 8.3.3.3 & 4.2.4 for data rates >>>>>>>>>>>> of 8.0 GT/s, 16.0 GT/s, 32.0 GT/s, and 64.0 GT/s, there is a way to >>>>>>>>>>>> configure lane equalization presets for each lane to enhance the PCIe >>>>>>>>>>>> link reliability. Each preset value represents a different combination >>>>>>>>>>>> of pre-shoot and de-emphasis values. For each data rate, different >>>>>>>>>>>> registers are defined: for 8.0 GT/s, registers are defined in section >>>>>>>>>>>> 7.7.3.4; for 16.0 GT/s, in section 7.7.5.9, etc. The 8.0 GT/s rate has >>>>>>>>>>>> an extra receiver preset hint, requiring 16 bits per lane, while the >>>>>>>>>>>> remaining data rates use 8 bits per lane. >>>>>>>>>>>> >>>>>>>>>>>> Based on the number of lanes and the supported data rate, this function >>>>>>>>>>>> reads the device tree property and stores in the presets structure. >>>>>>>>>>>> >>>>>>>>>>>> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com> >>>>>>>>>>>> --- >>>>>>>>>>>> drivers/pci/of.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ >>>>>>>>>>>> drivers/pci/pci.h | 17 +++++++++++++++-- >>>>>>>>>>>> 2 files changed, 60 insertions(+), 2 deletions(-) >>>>>>>>>>>> >>>>>>>>>>>> diff --git a/drivers/pci/of.c b/drivers/pci/of.c >>>>>>>>>>>> index dacea3fc5128..99e0e7ae12e9 100644 >>>>>>>>>>>> --- a/drivers/pci/of.c >>>>>>>>>>>> +++ b/drivers/pci/of.c >>>>>>>>>>>> @@ -826,3 +826,48 @@ u32 of_pci_get_slot_power_limit(struct device_node *node, >>>>>>>>>>>> return slot_power_limit_mw; >>>>>>>>>>>> } >>>>>>>>>>>> EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit); >>>>>>>>>>>> + >>>>>>>>>>> >>>>>>>>>>> kerneldoc? Define who should free the memory and how. >>>>>>>>>>> >>>>>>>>>> I will update this in next series. >>>>>>>>>> as we are allocating using devm_kzalloc it should be freed on driver >>>>>>>>>> detach, as no special freeing is required. >>>>>>>>>>>> +int of_pci_get_equalization_presets(struct device *dev, >>>>>>>>>>>> + struct pci_eq_presets *presets, >>>>>>>>>>>> + int num_lanes) >>>>>>>>>>>> +{ >>>>>>>>>>>> + char name[20]; >>>>>>>>>>>> + void **preset; >>>>>>>>>>>> + void *temp; >>>>>>>>>>>> + int ret; >>>>>>>>>>>> + >>>>>>>>>>>> + if (of_property_present(dev->of_node, "eq-presets-8gts")) { >>>>>>>>>>>> + presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * num_lanes, GFP_KERNEL); >>>>>>>>>>>> + if (!presets->eq_presets_8gts) >>>>>>>>>>>> + return -ENOMEM; >>>>>>>>>>>> + >>>>>>>>>>>> + ret = of_property_read_u16_array(dev->of_node, "eq-presets-8gts", >>>>>>>>>>>> + presets->eq_presets_8gts, num_lanes); >>>>>>>>>>>> + if (ret) { >>>>>>>>>>>> + dev_err(dev, "Error reading eq-presets-8gts %d\n", ret); >>>>>>>>>>>> + return ret; >>>>>>>>>>>> + } >>>>>>>>>>>> + } >>>>>>>>>>>> + >>>>>>>>>>>> + for (int i = 1; i < sizeof(struct pci_eq_presets) / sizeof(void *); i++) { >>>>>>>>>>>> + snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); >>>>>>>>>>>> + if (of_property_present(dev->of_node, name)) { >>>>>>>>>>>> + temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, GFP_KERNEL); >>>>>>>>>>>> + if (!temp) >>>>>>>>>>>> + return -ENOMEM; >>>>>>>>>>>> + >>>>>>>>>>>> + ret = of_property_read_u8_array(dev->of_node, name, >>>>>>>>>>>> + temp, num_lanes); >>>>>>>>>>>> + if (ret) { >>>>>>>>>>>> + dev_err(dev, "Error %s %d\n", name, ret); >>>>>>>>>>>> + return ret; >>>>>>>>>>>> + } >>>>>>>>>>>> + >>>>>>>>>>>> + preset = (void **)((u8 *)presets + i * sizeof(void *)); >>>>>>>>>>> >>>>>>>>>>> Ugh. >>>>>>>>>>> >>>>>>>>>> I was trying iterate over each element on the structure as presets holds the >>>>>>>>>> starting address of the structure and to that we are adding size of the void >>>>>>>>>> * point to go to each element. I did this way to reduce the >>>>>>>>>> redundant code to read all the gts which has same way of storing the data >>>>>>>>>> from the device tree. I will add comments here in the next series. >>>>>>>>> >>>>>>>>> Please rewrite this in a cleaner way. The code shouldn't raise >>>>>>>>> questions. >>>>>>>>> >>>>>>>>>>>> + *preset = temp; >>>>>>>>>>>> + } >>>>>>>>>>>> + } >>>>>>>>>>>> + >>>>>>>>>>>> + return 0; >>>>>>>>>>>> +} >>>>>>>>>>>> +EXPORT_SYMBOL_GPL(of_pci_get_equalization_presets); >>>>>>>>>>>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h >>>>>>>>>>>> index 14d00ce45bfa..82362d58bedc 100644 >>>>>>>>>>>> --- a/drivers/pci/pci.h >>>>>>>>>>>> +++ b/drivers/pci/pci.h >>>>>>>>>>>> @@ -731,7 +731,12 @@ static inline u64 pci_rebar_size_to_bytes(int size) >>>>>>>>>>>> } >>>>>>>>>>>> struct device_node; >>>>>>>>>>>> - >>>>>>>>>>>> +struct pci_eq_presets { >>>>>>>>>>>> + void *eq_presets_8gts; >>>>>>>>>>>> + void *eq_presets_16gts; >>>>>>>>>>>> + void *eq_presets_32gts; >>>>>>>>>>>> + void *eq_presets_64gts; >>>>>>>>>>> >>>>>>>>>>> Why are all of those void*? 8gts is u16*, all other are u8*. >>>>>>>>>>> >>>>>>>>>> To have common parsing logic I moved them to void*, as these are pointers >>>>>>>>>> actual memory is allocated by of_pci_get_equalization_presets() >>>>>>>>>> based upon the gts these should not give any issues. >>>>>>>>> >>>>>>>>> Please, don't. They have types. void pointers are for the opaque data. >>>>>>>>> >>>>>>>> ok. >>>>>>>> >>>>>>>> I think then better to use v1 patch >>>>>>>> https://lore.kernel.org/all/20241116-presets-v1-2-878a837a4fee@quicinc.com/ >>>>>>>> >>>>>>>> konrad, any objection on using v1 as that will be cleaner way even if we >>>>>>>> have some repetitive code. >>>>>>> >>>>>>> Konrad had a nice suggestion about using the array of values. Please use >>>>>>> such an array for 16gts and above. This removes most of repetitive code. >>>>>>> >>>>>> I don't feel having array in the preset structure looks good, I have >>>>>> come up with this logic if you feel it is not so good I will go to the >>>>>> suggested way by having array for 16gts and above. >>>>>> >>>>>> if (of_property_present(dev->of_node, "eq-presets-8gts")) { >>>>>> presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * >>>>>> num_lanes, GFP_KERNEL); >>>>>> if (!presets->eq_presets_8gts) >>>>>> return -ENOMEM; >>>>>> >>>>>> ret = of_property_read_u16_array(dev->of_node, >>>>>> "eq-presets-8gts", >>>>>> >>>>>> presets->eq_presets_8gts, num_lanes); >>>>>> if (ret) { >>>>>> dev_err(dev, "Error reading eq-presets-8gts %d\n", >>>>>> ret); >>>>>> return ret; >>>>>> } >>>>>> } >>>>>> >>>>>> for (int i = EQ_PRESET_TYPE_16GTS; i < EQ_PRESET_TYPE_64GTS; i++) { >>>>>> snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); >>>>>> if (of_property_present(dev->of_node, name)) { >>>>>> temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, >>>>>> GFP_KERNEL); >>>>>> if (!temp) >>>>>> return -ENOMEM; >>>>>> >>>>>> ret = of_property_read_u8_array(dev->of_node, name, >>>>>> temp, num_lanes); >>>>>> if (ret) { >>>>>> dev_err(dev, "Error %s %d\n", name, ret); >>>>>> return ret; >>>>>> } >>>>>> >>>>>> switch (i) { >>>>>> case EQ_PRESET_TYPE_16GTS: >>>>>> presets->eq_presets_16gts = temp; >>>>>> break; >>>>>> case EQ_PRESET_TYPE_32GTS: >>>>>> presets->eq_presets_32gts = temp; >>>>>> break; >>>>>> case EQ_PRESET_TYPE_64GTS: >>>>>> presets->eq_presets_64gts = temp; >>>>>> break; >>>>>> } >>>>> >>>>> This looks like 'presets->eq_presets[i] = temp;', but I won't insist on >>>>> that. >>>>> >>>>> Also, a strange thought came to my mind: we know that there won't be >>>>> more than 16 lanes. Can we have the following structure instead: >>>>> >>>>> #define MAX_LANES 16 >>>>> enum pcie_gts { >>>>> PCIE_GTS_16GTS, >>>>> PCIE_GTS_32GTS, >>>>> PCIE_GTS_64GTS, >>>>> PCIE_GTS_MAX, >>>>> }; >>>>> struct pci_eq_presets { >>>>> u16 eq_presets_8gts[MAX_LANES]; >>>>> u8 eq_presets_Ngts[PCIE_GTS_MAX][MAX_LANES]; >>>>> }; >>>>> >>>>> This should allow you to drop the of_property_present() and >>>>> devm_kzalloc(). Just read DT data into a corresponding array. >>>>> >>>> in the dwc driver patch I was using pointers and memory allocation >>>> to known if the property is present or not. If I use this way I might >>>> end up reading dt property again. >>> >>> Add foo_valid flags to the struct. >> >> Some(u8)/None would be fitting, but we're not there yet :( >> >> Are all 0x00-0xff(ff) values valid for these presets? >> > currently 0xff are reserved not sure in future PCIe spec data rates > can use it or not. Maybe we could use it as a #define-d placeholder then, and kick the can down the road. Opinions? Konrad
diff --git a/drivers/pci/of.c b/drivers/pci/of.c index dacea3fc5128..99e0e7ae12e9 100644 --- a/drivers/pci/of.c +++ b/drivers/pci/of.c @@ -826,3 +826,48 @@ u32 of_pci_get_slot_power_limit(struct device_node *node, return slot_power_limit_mw; } EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit); + +int of_pci_get_equalization_presets(struct device *dev, + struct pci_eq_presets *presets, + int num_lanes) +{ + char name[20]; + void **preset; + void *temp; + int ret; + + if (of_property_present(dev->of_node, "eq-presets-8gts")) { + presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * num_lanes, GFP_KERNEL); + if (!presets->eq_presets_8gts) + return -ENOMEM; + + ret = of_property_read_u16_array(dev->of_node, "eq-presets-8gts", + presets->eq_presets_8gts, num_lanes); + if (ret) { + dev_err(dev, "Error reading eq-presets-8gts %d\n", ret); + return ret; + } + } + + for (int i = 1; i < sizeof(struct pci_eq_presets) / sizeof(void *); i++) { + snprintf(name, sizeof(name), "eq-presets-%dgts", 8 << i); + if (of_property_present(dev->of_node, name)) { + temp = devm_kzalloc(dev, sizeof(u8) * num_lanes, GFP_KERNEL); + if (!temp) + return -ENOMEM; + + ret = of_property_read_u8_array(dev->of_node, name, + temp, num_lanes); + if (ret) { + dev_err(dev, "Error %s %d\n", name, ret); + return ret; + } + + preset = (void **)((u8 *)presets + i * sizeof(void *)); + *preset = temp; + } + } + + return 0; +} +EXPORT_SYMBOL_GPL(of_pci_get_equalization_presets); diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index 14d00ce45bfa..82362d58bedc 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -731,7 +731,12 @@ static inline u64 pci_rebar_size_to_bytes(int size) } struct device_node; - +struct pci_eq_presets { + void *eq_presets_8gts; + void *eq_presets_16gts; + void *eq_presets_32gts; + void *eq_presets_64gts; +}; #ifdef CONFIG_OF int of_pci_parse_bus_range(struct device_node *node, struct resource *res); int of_get_pci_domain_nr(struct device_node *node); @@ -746,7 +751,9 @@ void pci_set_bus_of_node(struct pci_bus *bus); void pci_release_bus_of_node(struct pci_bus *bus); int devm_of_pci_bridge_init(struct device *dev, struct pci_host_bridge *bridge); - +int of_pci_get_equalization_presets(struct device *dev, + struct pci_eq_presets *presets, + int num_lanes); #else static inline int of_pci_parse_bus_range(struct device_node *node, struct resource *res) @@ -793,6 +800,12 @@ static inline int devm_of_pci_bridge_init(struct device *dev, struct pci_host_br return 0; } +static inline int of_pci_get_equalization_presets(struct device *dev, + struct pci_eq_presets *presets, + int num_lanes) +{ + return 0; +} #endif /* CONFIG_OF */ struct of_changeset;
PCIe equalization presets are predefined settings used to optimize signal integrity by compensating for signal loss and distortion in high-speed data transmission. As per PCIe spec 6.0.1 revision section 8.3.3.3 & 4.2.4 for data rates of 8.0 GT/s, 16.0 GT/s, 32.0 GT/s, and 64.0 GT/s, there is a way to configure lane equalization presets for each lane to enhance the PCIe link reliability. Each preset value represents a different combination of pre-shoot and de-emphasis values. For each data rate, different registers are defined: for 8.0 GT/s, registers are defined in section 7.7.3.4; for 16.0 GT/s, in section 7.7.5.9, etc. The 8.0 GT/s rate has an extra receiver preset hint, requiring 16 bits per lane, while the remaining data rates use 8 bits per lane. Based on the number of lanes and the supported data rate, this function reads the device tree property and stores in the presets structure. Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com> --- drivers/pci/of.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ drivers/pci/pci.h | 17 +++++++++++++++-- 2 files changed, 60 insertions(+), 2 deletions(-)