| Message ID | 1708697021-16877-2-git-send-email-quic_msarkar@quicinc.com |
|---|---|
| State | New |
| Headers | show |
| Series | arm64: qcom: sa8775p: add cache coherency support for SA8775P | expand |
On Fri, Feb 23, 2024 at 07:33:38PM +0530, Mrinmay Sarkar wrote: Subject should be: "PCI: qcom: Override NO_SNOOP attribute for SA8775P" > Due to some hardware changes, SA8775P has set the NO_SNOOP attribute > in its TLP for all the PCIe controllers. NO_SNOOP attribute when set, > the requester is indicating that there no cache coherency issues exit > for the addressed memory on the host i.e., memory is not cached. But s/host/endpoint > in reality, requester cannot assume this unless there is a complete > control/visibility over the addressed memory on the host. > s/host/endpoint > And worst case, if the memory is cached on the host, it may lead to s/host/endpoint > memory corruption issues. It should be noted that the caching of memory > on the host is not solely dependent on the NO_SNOOP attribute in TLP. > s/host/endpoint > So to avoid the corruption, this patch overrides the NO_SNOOP attribute > by setting the PCIE_PARF_NO_SNOOP_OVERIDE register. This patch is not > needed for other upstream supported platforms since they do not set > NO_SNOOP attribute by default. > > 8775 has IP version 1.34.0 so intruduce a new cfg(cfg_1_34_0) for this > platform. Assign enable_cache_snoop flag into struct qcom_pcie_cfg and > set it true in cfg_1_34_0 and enable cache snooping if this particular > flag is true. > > Signed-off-by: Mrinmay Sarkar <quic_msarkar@quicinc.com> > --- > drivers/pci/controller/dwc/pcie-qcom.c | 20 +++++++++++++++++++- > 1 file changed, 19 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c > index 2ce2a3bd932b..872be7f7d7b3 100644 > --- a/drivers/pci/controller/dwc/pcie-qcom.c > +++ b/drivers/pci/controller/dwc/pcie-qcom.c > @@ -51,6 +51,7 @@ > #define PARF_SID_OFFSET 0x234 > #define PARF_BDF_TRANSLATE_CFG 0x24c > #define PARF_SLV_ADDR_SPACE_SIZE 0x358 > +#define PARF_NO_SNOOP_OVERIDE 0x3d4 > #define PARF_DEVICE_TYPE 0x1000 > #define PARF_BDF_TO_SID_TABLE_N 0x2000 > > @@ -117,6 +118,10 @@ > /* PARF_LTSSM register fields */ > #define LTSSM_EN BIT(8) > > +/* PARF_NO_SNOOP_OVERIDE register fields */ > +#define WR_NO_SNOOP_OVERIDE_EN BIT(1) > +#define RD_NO_SNOOP_OVERIDE_EN BIT(3) > + > /* PARF_DEVICE_TYPE register fields */ > #define DEVICE_TYPE_RC 0x4 > > @@ -229,6 +234,7 @@ struct qcom_pcie_ops { > Please add Kdoc comments for this struct. And describe the "override_no_snoop" member as below: "Override NO_SNOOP attribute in TLP to enable cache snooping" > struct qcom_pcie_cfg { > const struct qcom_pcie_ops *ops; > + bool enable_cache_snoop; Rename this to "override_no_snoop" > }; > > struct qcom_pcie { > @@ -961,6 +967,13 @@ static int qcom_pcie_init_2_7_0(struct qcom_pcie *pcie) > > static int qcom_pcie_post_init_2_7_0(struct qcom_pcie *pcie) > { > + const struct qcom_pcie_cfg *pcie_cfg = pcie->cfg; > + > + /* Enable cache snooping for SA8775P */ Remove this comment in favor of Kdoc mentioned above. - Mani
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c index 2ce2a3bd932b..872be7f7d7b3 100644 --- a/drivers/pci/controller/dwc/pcie-qcom.c +++ b/drivers/pci/controller/dwc/pcie-qcom.c @@ -51,6 +51,7 @@ #define PARF_SID_OFFSET 0x234 #define PARF_BDF_TRANSLATE_CFG 0x24c #define PARF_SLV_ADDR_SPACE_SIZE 0x358 +#define PARF_NO_SNOOP_OVERIDE 0x3d4 #define PARF_DEVICE_TYPE 0x1000 #define PARF_BDF_TO_SID_TABLE_N 0x2000 @@ -117,6 +118,10 @@ /* PARF_LTSSM register fields */ #define LTSSM_EN BIT(8) +/* PARF_NO_SNOOP_OVERIDE register fields */ +#define WR_NO_SNOOP_OVERIDE_EN BIT(1) +#define RD_NO_SNOOP_OVERIDE_EN BIT(3) + /* PARF_DEVICE_TYPE register fields */ #define DEVICE_TYPE_RC 0x4 @@ -229,6 +234,7 @@ struct qcom_pcie_ops { struct qcom_pcie_cfg { const struct qcom_pcie_ops *ops; + bool enable_cache_snoop; }; struct qcom_pcie { @@ -961,6 +967,13 @@ static int qcom_pcie_init_2_7_0(struct qcom_pcie *pcie) static int qcom_pcie_post_init_2_7_0(struct qcom_pcie *pcie) { + const struct qcom_pcie_cfg *pcie_cfg = pcie->cfg; + + /* Enable cache snooping for SA8775P */ + if (pcie_cfg->enable_cache_snoop) + writel(WR_NO_SNOOP_OVERIDE_EN | RD_NO_SNOOP_OVERIDE_EN, + pcie->parf + PARF_NO_SNOOP_OVERIDE); + qcom_pcie_clear_hpc(pcie->pci); return 0; @@ -1334,6 +1347,11 @@ static const struct qcom_pcie_cfg cfg_1_9_0 = { .ops = &ops_1_9_0, }; +static const struct qcom_pcie_cfg cfg_1_34_0 = { + .ops = &ops_1_9_0, + .enable_cache_snoop = true, +}; + static const struct qcom_pcie_cfg cfg_2_1_0 = { .ops = &ops_2_1_0, }; @@ -1630,7 +1648,7 @@ static const struct of_device_id qcom_pcie_match[] = { { .compatible = "qcom,pcie-msm8996", .data = &cfg_2_3_2 }, { .compatible = "qcom,pcie-qcs404", .data = &cfg_2_4_0 }, { .compatible = "qcom,pcie-sa8540p", .data = &cfg_1_9_0 }, - { .compatible = "qcom,pcie-sa8775p", .data = &cfg_1_9_0}, + { .compatible = "qcom,pcie-sa8775p", .data = &cfg_1_34_0}, { .compatible = "qcom,pcie-sc7280", .data = &cfg_1_9_0 }, { .compatible = "qcom,pcie-sc8180x", .data = &cfg_1_9_0 }, { .compatible = "qcom,pcie-sc8280xp", .data = &cfg_1_9_0 },
Due to some hardware changes, SA8775P has set the NO_SNOOP attribute in its TLP for all the PCIe controllers. NO_SNOOP attribute when set, the requester is indicating that there no cache coherency issues exit for the addressed memory on the host i.e., memory is not cached. But in reality, requester cannot assume this unless there is a complete control/visibility over the addressed memory on the host. And worst case, if the memory is cached on the host, it may lead to memory corruption issues. It should be noted that the caching of memory on the host is not solely dependent on the NO_SNOOP attribute in TLP. So to avoid the corruption, this patch overrides the NO_SNOOP attribute by setting the PCIE_PARF_NO_SNOOP_OVERIDE register. This patch is not needed for other upstream supported platforms since they do not set NO_SNOOP attribute by default. 8775 has IP version 1.34.0 so intruduce a new cfg(cfg_1_34_0) for this platform. Assign enable_cache_snoop flag into struct qcom_pcie_cfg and set it true in cfg_1_34_0 and enable cache snooping if this particular flag is true. Signed-off-by: Mrinmay Sarkar <quic_msarkar@quicinc.com> --- drivers/pci/controller/dwc/pcie-qcom.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-)