| Message ID | 20170321163122.9183-3-fu.wei@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | acpi, clocksource: add GTDT driver and GTDT support in arm_arch_timer | expand |
On Wed, Mar 29, 2017 at 01:11:58PM +0800, Fu Wei wrote: > Hi Daniel, > > On 29 March 2017 at 11:41, Fu Wei <fu.wei@linaro.org> wrote: > > Hi Daniel, > > > > Great thanks for your review, allow me to answer your question below: > > > > On 28 March 2017 at 22:58, Daniel Lezcano <daniel.lezcano@linaro.org> wrote: > >> On Wed, Mar 22, 2017 at 12:31:13AM +0800, fu.wei@linaro.org wrote: > >>> From: Fu Wei <fu.wei@linaro.org> > >>> > >>> Currently, the counter frequency detection call(arch_timer_detect_rate) > >>> includes getting the frequency from the device-tree property, the per-cpu > >>> arch-timer and the memory-mapped (MMIO) timer interfaces. > >>> But reading device-tree property will be needed only when system boot with > >>> device-tree, and reading from the per-cpu arch-timer and the memory-mapped > >>> (MMIO) timer interfaces will be needed only when the system initializes > >>> the relevant timer. > >>> > >>> This patch separates out device-tree code, keep them in device-tree init > >>> function, and removes arch_timer_detect_rate founction, then uses the > >>> arch_timer_get_cntfrq and arch_timer_mem_get_cntfrq directly. > >>> > >>> Signed-off-by: Fu Wei <fu.wei@linaro.org> > >>> --- > >>> drivers/clocksource/arm_arch_timer.c | 58 +++++++++++++++++++----------------- > >>> 1 file changed, 30 insertions(+), 28 deletions(-) > >>> > >>> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c > >>> index 843f923..29ca7d6 100644 > >>> --- a/drivers/clocksource/arm_arch_timer.c > >>> +++ b/drivers/clocksource/arm_arch_timer.c > >>> @@ -560,30 +560,6 @@ static u32 arch_timer_mem_get_cntfrq(void __iomem *cntbase) > >>> return readl_relaxed(cntbase + CNTFRQ); > >>> } > >>> > >>> -static void > >>> -arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np) > >>> -{ > >>> - /* Who has more than one independent system counter? */ > >>> - if (arch_timer_rate) > >>> - return; > >>> - > >>> - /* > >>> - * Try to determine the frequency from the device tree or CNTFRQ, > >>> - * if ACPI is enabled, get the frequency from CNTFRQ ONLY. > >>> - */ > >>> - if (!acpi_disabled || > >>> - of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) { > >>> - if (cntbase) > >>> - arch_timer_rate = arch_timer_mem_get_cntfrq(cntbase); > >>> - else > >>> - arch_timer_rate = arch_timer_get_cntfrq(); > >>> - } > >>> - > >>> - /* Check the timer frequency. */ > >>> - if (arch_timer_rate == 0) > >>> - pr_warn("frequency not available\n"); > >>> -} > >>> - > >>> static void arch_timer_banner(unsigned type) > >>> { > >>> pr_info("%s%s%s timer(s) running at %lu.%02luMHz (%s%s%s).\n", > >>> @@ -958,7 +934,17 @@ static int __init arch_timer_of_init(struct device_node *np) > >>> for (i = ARCH_TIMER_PHYS_SECURE_PPI; i < ARCH_TIMER_MAX_TIMER_PPI; i++) > >>> arch_timer_ppi[i] = irq_of_parse_and_map(np, i); > >>> > >>> - arch_timer_detect_rate(NULL, np); > >>> + /* > >>> + * Try to determine the frequency from the device tree, > >>> + * if fail, get the frequency from the sysreg CNTFRQ. > >>> + */ > >>> + if (!arch_timer_rate && > >> > >> This variable is set only if "arm,armv7-timer" and "arm,armv7-timer-mem" are > >> declared together in the DT, right ? > >> > >> Two declarations for a single variable ? Ignore the !arch_timer_rate. > > > > In this function, we try to initialize per-CPU arm arch_timer by DT. > > this "!arch_timer_rate" is for testing that if we have got system > > counter frequency from the memory-mapped timer. If so, we just skip > > getting the frequency from DT or sysreg cntfrq again. > > This variable is set only if "arm,armv7-timer-mem" is initialized > > earlier than "arm,armv7-timer", in another word, maybe the node of > > "arm,armv7-timer-mem" is declared earlier than "arm,armv7-timer-mem" > > one in DT. > > > > we do this check is for keeping the same init logic as before in the > > DT, try to avoid any possibility of breaking devices which boot by > > DT. > > > >> > >>> + of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) > >>> + arch_timer_rate = arch_timer_get_cntfrq(); > >>> + if (!arch_timer_rate) { > >>> + pr_err(FW_BUG "frequency not available.\n"); > >>> + return -EINVAL; > >>> + } > >> > >> Please, clarify this block, the conditions are unclear. > > > > this "!arch_timer_rate" is for verifying that if the system counter > > frequency we just got from DT or sysreg cntfrq is valid(non-zero). > > > > So here, you can see I check arch_timer_rate twice, but they are for > > different cases. > > I think about this several times, > For this block, it is a little unclear, so I think this will be better: > > + /* > + * Try to determine the frequency: > + * If we have got it in arch_timer_mem_of_init, we don't need to get > it again, skip. > + * Otherwise, try to get the frequency from the device tree, > + * if fail, try to get it from the sysreg CNTFRQ. > + * Last, verify the arch_timer_rate before leaving this block. > + */ > + if (!arch_timer_rate) { > + if (of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) > + arch_timer_rate = arch_timer_get_cntfrq(); > + if (!arch_timer_rate) { > + pr_err(FW_BUG "frequency not available.\n"); > + return -EINVAL; > + } > + } Hi Fu Wei, in my previous comment, I was suggesting to remove the first arch_timer_rate check. The code assumes something else initialized this variable. There is clearly a conflict in the variable assignment. So if a node is defined twice for this variable, then it is more sane to consider the second pass overwrites the first one. As the DT are specifying the same rate, for -mem and !-mem, then it should have not an impact (to be verified).
On 29 March 2017 at 22:41, Daniel Lezcano <daniel.lezcano@linaro.org> wrote: > On Wed, Mar 29, 2017 at 01:11:58PM +0800, Fu Wei wrote: >> Hi Daniel, >> >> On 29 March 2017 at 11:41, Fu Wei <fu.wei@linaro.org> wrote: >> > Hi Daniel, >> > >> > Great thanks for your review, allow me to answer your question below: >> > >> > On 28 March 2017 at 22:58, Daniel Lezcano <daniel.lezcano@linaro.org> wrote: >> >> On Wed, Mar 22, 2017 at 12:31:13AM +0800, fu.wei@linaro.org wrote: >> >>> From: Fu Wei <fu.wei@linaro.org> >> >>> >> >>> Currently, the counter frequency detection call(arch_timer_detect_rate) >> >>> includes getting the frequency from the device-tree property, the per-cpu >> >>> arch-timer and the memory-mapped (MMIO) timer interfaces. >> >>> But reading device-tree property will be needed only when system boot with >> >>> device-tree, and reading from the per-cpu arch-timer and the memory-mapped >> >>> (MMIO) timer interfaces will be needed only when the system initializes >> >>> the relevant timer. >> >>> >> >>> This patch separates out device-tree code, keep them in device-tree init >> >>> function, and removes arch_timer_detect_rate founction, then uses the >> >>> arch_timer_get_cntfrq and arch_timer_mem_get_cntfrq directly. >> >>> >> >>> Signed-off-by: Fu Wei <fu.wei@linaro.org> >> >>> --- >> >>> drivers/clocksource/arm_arch_timer.c | 58 +++++++++++++++++++----------------- >> >>> 1 file changed, 30 insertions(+), 28 deletions(-) >> >>> >> >>> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c >> >>> index 843f923..29ca7d6 100644 >> >>> --- a/drivers/clocksource/arm_arch_timer.c >> >>> +++ b/drivers/clocksource/arm_arch_timer.c >> >>> @@ -560,30 +560,6 @@ static u32 arch_timer_mem_get_cntfrq(void __iomem *cntbase) >> >>> return readl_relaxed(cntbase + CNTFRQ); >> >>> } >> >>> >> >>> -static void >> >>> -arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np) >> >>> -{ >> >>> - /* Who has more than one independent system counter? */ >> >>> - if (arch_timer_rate) >> >>> - return; >> >>> - >> >>> - /* >> >>> - * Try to determine the frequency from the device tree or CNTFRQ, >> >>> - * if ACPI is enabled, get the frequency from CNTFRQ ONLY. >> >>> - */ >> >>> - if (!acpi_disabled || >> >>> - of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) { >> >>> - if (cntbase) >> >>> - arch_timer_rate = arch_timer_mem_get_cntfrq(cntbase); >> >>> - else >> >>> - arch_timer_rate = arch_timer_get_cntfrq(); >> >>> - } >> >>> - >> >>> - /* Check the timer frequency. */ >> >>> - if (arch_timer_rate == 0) >> >>> - pr_warn("frequency not available\n"); >> >>> -} >> >>> - >> >>> static void arch_timer_banner(unsigned type) >> >>> { >> >>> pr_info("%s%s%s timer(s) running at %lu.%02luMHz (%s%s%s).\n", >> >>> @@ -958,7 +934,17 @@ static int __init arch_timer_of_init(struct device_node *np) >> >>> for (i = ARCH_TIMER_PHYS_SECURE_PPI; i < ARCH_TIMER_MAX_TIMER_PPI; i++) >> >>> arch_timer_ppi[i] = irq_of_parse_and_map(np, i); >> >>> >> >>> - arch_timer_detect_rate(NULL, np); >> >>> + /* >> >>> + * Try to determine the frequency from the device tree, >> >>> + * if fail, get the frequency from the sysreg CNTFRQ. >> >>> + */ >> >>> + if (!arch_timer_rate && >> >> >> >> This variable is set only if "arm,armv7-timer" and "arm,armv7-timer-mem" are >> >> declared together in the DT, right ? >> >> >> >> Two declarations for a single variable ? Ignore the !arch_timer_rate. >> > >> > In this function, we try to initialize per-CPU arm arch_timer by DT. >> > this "!arch_timer_rate" is for testing that if we have got system >> > counter frequency from the memory-mapped timer. If so, we just skip >> > getting the frequency from DT or sysreg cntfrq again. >> > This variable is set only if "arm,armv7-timer-mem" is initialized >> > earlier than "arm,armv7-timer", in another word, maybe the node of >> > "arm,armv7-timer-mem" is declared earlier than "arm,armv7-timer-mem" >> > one in DT. >> > >> > we do this check is for keeping the same init logic as before in the >> > DT, try to avoid any possibility of breaking devices which boot by >> > DT. >> > >> >> >> >>> + of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) >> >>> + arch_timer_rate = arch_timer_get_cntfrq(); >> >>> + if (!arch_timer_rate) { >> >>> + pr_err(FW_BUG "frequency not available.\n"); >> >>> + return -EINVAL; >> >>> + } >> >> >> >> Please, clarify this block, the conditions are unclear. >> > >> > this "!arch_timer_rate" is for verifying that if the system counter >> > frequency we just got from DT or sysreg cntfrq is valid(non-zero). >> > >> > So here, you can see I check arch_timer_rate twice, but they are for >> > different cases. >> >> I think about this several times, >> For this block, it is a little unclear, so I think this will be better: >> >> + /* >> + * Try to determine the frequency: >> + * If we have got it in arch_timer_mem_of_init, we don't need to get >> it again, skip. >> + * Otherwise, try to get the frequency from the device tree, >> + * if fail, try to get it from the sysreg CNTFRQ. >> + * Last, verify the arch_timer_rate before leaving this block. >> + */ >> + if (!arch_timer_rate) { >> + if (of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) >> + arch_timer_rate = arch_timer_get_cntfrq(); >> + if (!arch_timer_rate) { >> + pr_err(FW_BUG "frequency not available.\n"); >> + return -EINVAL; >> + } >> + } > > Hi Fu Wei, > > in my previous comment, I was suggesting to remove the first arch_timer_rate > check. > > The code assumes something else initialized this variable. There is clearly a > conflict in the variable assignment. So if a node is defined twice for this > variable, then it is more sane to consider the second pass overwrites the first > one. As the DT are specifying the same rate, for -mem and !-mem, then it should > have not an impact (to be verified). So the code will be like this: + /* + * Try to determine the frequency: + * If we try to get the frequency from the device tree, + * if fail, try to get it from the sysreg CNTFRQ. + * Then verify the arch_timer_rate. + */ + if (of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) + arch_timer_rate = arch_timer_get_cntfrq(); + if (!arch_timer_rate) { + pr_err(FW_BUG "frequency not available.\n"); + return -EINVAL; + } I am OK to delete the first arch_timer_rate check, If arch_timer_mem is initialized first, we just overwrite the existing rate to arch_timer rate. This makes sense to me. -- Best regards, Fu Wei Software Engineer Red Hat
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 843f923..29ca7d6 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -560,30 +560,6 @@ static u32 arch_timer_mem_get_cntfrq(void __iomem *cntbase) return readl_relaxed(cntbase + CNTFRQ); } -static void -arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np) -{ - /* Who has more than one independent system counter? */ - if (arch_timer_rate) - return; - - /* - * Try to determine the frequency from the device tree or CNTFRQ, - * if ACPI is enabled, get the frequency from CNTFRQ ONLY. - */ - if (!acpi_disabled || - of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) { - if (cntbase) - arch_timer_rate = arch_timer_mem_get_cntfrq(cntbase); - else - arch_timer_rate = arch_timer_get_cntfrq(); - } - - /* Check the timer frequency. */ - if (arch_timer_rate == 0) - pr_warn("frequency not available\n"); -} - static void arch_timer_banner(unsigned type) { pr_info("%s%s%s timer(s) running at %lu.%02luMHz (%s%s%s).\n", @@ -958,7 +934,17 @@ static int __init arch_timer_of_init(struct device_node *np) for (i = ARCH_TIMER_PHYS_SECURE_PPI; i < ARCH_TIMER_MAX_TIMER_PPI; i++) arch_timer_ppi[i] = irq_of_parse_and_map(np, i); - arch_timer_detect_rate(NULL, np); + /* + * Try to determine the frequency from the device tree, + * if fail, get the frequency from the sysreg CNTFRQ. + */ + if (!arch_timer_rate && + of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) + arch_timer_rate = arch_timer_get_cntfrq(); + if (!arch_timer_rate) { + pr_err(FW_BUG "frequency not available.\n"); + return -EINVAL; + } arch_timer_c3stop = !of_property_read_bool(np, "always-on"); @@ -1069,7 +1055,19 @@ static int __init arch_timer_mem_init(struct device_node *np) goto out; } - arch_timer_detect_rate(base, np); + /* + * Try to determine the frequency from the device tree, + * if fail, get the frequency from the CNTFRQ reg of MMIO timer. + */ + if (!arch_timer_rate && + of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) + arch_timer_rate = arch_timer_mem_get_cntfrq(base); + if (!arch_timer_rate) { + pr_err(FW_BUG "MMIO frequency not available.\n"); + ret = -EINVAL; + goto out; + } + ret = arch_timer_mem_register(base, irq); if (ret) goto out; @@ -1130,8 +1128,12 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table) map_generic_timer_interrupt(gtdt->non_secure_el2_interrupt, gtdt->non_secure_el2_flags); - /* Get the frequency from CNTFRQ */ - arch_timer_detect_rate(NULL, NULL); + /* Get the frequency from the sysreg CNTFRQ */ + arch_timer_rate = arch_timer_get_cntfrq(); + if (!arch_timer_rate) { + pr_err(FW_BUG "frequency not available.\n"); + return -EINVAL; + } arch_timer_uses_ppi = arch_timer_select_ppi(); if (!arch_timer_ppi[arch_timer_uses_ppi]) {