| Message ID | 20161221064603.11830-7-fu.wei@linaro.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Wed, Dec 21, 2016 at 02:45:54PM +0800, fu.wei@linaro.org wrote: > From: Fu Wei <fu.wei@linaro.org> > > Currently, the counter frequency detection call(arch_timer_detect_rate) > combines all the ways to get counter frequency: device-tree property, > system coprocessor register, MMIO timer. But in the most of use cases, > we don't need all the ways to try: > For example, reading device-tree property will be needed only when > system boot with device-tree, getting frequency from MMIO timer register > will beneeded only when we init MMIO timer. > > This patch separates paths to determine frequency: > Separate out device-tree code, keep them in device-tree init function. Splitting these out makes sense to me. > Separate out the MMIO frequency and the sysreg frequency detection call, > and use the appropriate one for the counter. > Signed-off-by: Fu Wei <fu.wei@linaro.org> > Tested-by: Xiongfeng Wang <wangxiongfeng2@huawei.com> > --- > drivers/clocksource/arm_arch_timer.c | 49 +++++++++++++++++++++++------------- > 1 file changed, 31 insertions(+), 18 deletions(-) > > diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c > index c7b4482..9a1f138 100644 > --- a/drivers/clocksource/arm_arch_timer.c > +++ b/drivers/clocksource/arm_arch_timer.c > @@ -488,27 +488,31 @@ static int arch_timer_starting_cpu(unsigned int cpu) > return 0; > } > > -static void > -arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np) > +static void arch_timer_detect_rate(void) > { > - /* Who has more than one independent system counter? */ > - if (arch_timer_rate) > - return; > + /* > + * Try to get the timer frequency from > + * cntfrq_el0(system coprocessor register). > + */ > + if (!arch_timer_rate) > + arch_timer_rate = arch_timer_get_cntfrq(); > + > + /* Check the timer frequency. */ > + if (!arch_timer_rate) > + pr_warn("frequency not available\n"); > +} > > +static void arch_timer_mem_detect_rate(void __iomem *cntbase) > +{ > /* > - * Try to determine the frequency from the device tree or CNTFRQ, > - * if ACPI is enabled, get the frequency from CNTFRQ ONLY. > + * Try to determine the frequency from > + * CNTFRQ in memory-mapped timer. > */ > - if (!acpi_disabled || > - of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) { > - if (cntbase) > - arch_timer_rate = readl_relaxed(cntbase + CNTFRQ); > - else > - arch_timer_rate = arch_timer_get_cntfrq(); > - } > + if (!arch_timer_rate) > + arch_timer_rate = readl_relaxed(cntbase + CNTFRQ); > > /* Check the timer frequency. */ > - if (arch_timer_rate == 0) > + if (!arch_timer_rate) > pr_warn("frequency not available\n"); > } There's a subtle change in behaviour here. Previously for ACPI we'd only ever use the sysreg CNTFRQ value for arch_timer_rate, whereas now we might use the MMIO timer rate. Maybe that's not a big deal, but I will need to think. Generally, the logic to determine the rate is fairly gnarly regardless. It would be nice if we could split the MMIO and sysreg rates entirely, and kill the implicit relationship between the two, or at least make one canonical and warn if the two differ. Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Mark, On 17 January 2017 at 01:50, Mark Rutland <mark.rutland@arm.com> wrote: > On Wed, Dec 21, 2016 at 02:45:54PM +0800, fu.wei@linaro.org wrote: >> From: Fu Wei <fu.wei@linaro.org> >> >> Currently, the counter frequency detection call(arch_timer_detect_rate) >> combines all the ways to get counter frequency: device-tree property, >> system coprocessor register, MMIO timer. But in the most of use cases, >> we don't need all the ways to try: >> For example, reading device-tree property will be needed only when >> system boot with device-tree, getting frequency from MMIO timer register >> will beneeded only when we init MMIO timer. >> >> This patch separates paths to determine frequency: >> Separate out device-tree code, keep them in device-tree init function. > > Splitting these out makes sense to me. OK , will do > >> Separate out the MMIO frequency and the sysreg frequency detection call, >> and use the appropriate one for the counter. > >> Signed-off-by: Fu Wei <fu.wei@linaro.org> >> Tested-by: Xiongfeng Wang <wangxiongfeng2@huawei.com> >> --- >> drivers/clocksource/arm_arch_timer.c | 49 +++++++++++++++++++++++------------- >> 1 file changed, 31 insertions(+), 18 deletions(-) >> >> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c >> index c7b4482..9a1f138 100644 >> --- a/drivers/clocksource/arm_arch_timer.c >> +++ b/drivers/clocksource/arm_arch_timer.c >> @@ -488,27 +488,31 @@ static int arch_timer_starting_cpu(unsigned int cpu) >> return 0; >> } >> >> -static void >> -arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np) >> +static void arch_timer_detect_rate(void) >> { >> - /* Who has more than one independent system counter? */ >> - if (arch_timer_rate) >> - return; >> + /* >> + * Try to get the timer frequency from >> + * cntfrq_el0(system coprocessor register). >> + */ >> + if (!arch_timer_rate) >> + arch_timer_rate = arch_timer_get_cntfrq(); >> + >> + /* Check the timer frequency. */ >> + if (!arch_timer_rate) >> + pr_warn("frequency not available\n"); >> +} >> >> +static void arch_timer_mem_detect_rate(void __iomem *cntbase) >> +{ >> /* >> - * Try to determine the frequency from the device tree or CNTFRQ, >> - * if ACPI is enabled, get the frequency from CNTFRQ ONLY. >> + * Try to determine the frequency from >> + * CNTFRQ in memory-mapped timer. >> */ >> - if (!acpi_disabled || >> - of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) { >> - if (cntbase) >> - arch_timer_rate = readl_relaxed(cntbase + CNTFRQ); >> - else >> - arch_timer_rate = arch_timer_get_cntfrq(); >> - } >> + if (!arch_timer_rate) >> + arch_timer_rate = readl_relaxed(cntbase + CNTFRQ); >> >> /* Check the timer frequency. */ >> - if (arch_timer_rate == 0) >> + if (!arch_timer_rate) I think you mean this one, this is for keeping consistency with arch_timer_detect_rate. >> pr_warn("frequency not available\n"); >> } > > There's a subtle change in behaviour here. Previously for ACPI we'd only > ever use the sysreg CNTFRQ value for arch_timer_rate, whereas now we > might use the MMIO timer rate. Maybe that's not a big deal, but I will > need to think. > > Generally, the logic to determine the rate is fairly gnarly regardless. > > It would be nice if we could split the MMIO and sysreg rates entirely, Yes, I am doing this way, For sysreg rates, static void arch_timer_detect_rate(void) { /* * Try to get the timer frequency from * cntfrq_el0(system coprocessor register). */ if (!arch_timer_rate) arch_timer_rate = arch_timer_get_cntfrq(); /* Check the timer frequency. */ if (!arch_timer_rate) pr_warn("frequency not available\n"); } For MMIO timer, static void arch_timer_mem_detect_rate(void __iomem *cntbase) { /* * Try to determine the frequency from * CNTFRQ in memory-mapped timer. */ if (!arch_timer_rate) arch_timer_rate = readl_relaxed(cntbase + CNTFRQ); /* Check the timer frequency. */ if (!arch_timer_rate) pr_warn("frequency not available\n"); } in arch_time_*_init, only call arch_timer_detect_rate, in arch_timer_mem_init, only call arch_timer_mem_detect_rate. But you are right, this is fairly gnarly regardless. > and kill the implicit relationship between the two, or at least make one > canonical and warn if the two differ. So I think maybe we can do this: static void __arch_timer_determine_rate(u32 rate) { /* Check the timer frequency. */ if (!arch_timer_rate) if (rate) arch_timer_rate = rate; else pr_warn("frequency not available\n"); else if (arch_timer_rate != rate) pr_warn("got different frequency, keep original.\n"); } static void arch_timer_detect_rate(void) { /* * Try to get the timer frequency from * cntfrq_el0(system coprocessor register). */ __arch_timer_determine_rate(arch_timer_get_cntfrq()); } static void arch_timer_mem_detect_rate(void __iomem *cntbase) { /* * Try to get the timer frequency from * CNTFRQ in the MMIO timer. */ __arch_timer_determine_rate(readl_relaxed(cntbase + CNTFRQ)); } any thought? > > Thanks, > Mark.
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index c7b4482..9a1f138 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -488,27 +488,31 @@ static int arch_timer_starting_cpu(unsigned int cpu) return 0; } -static void -arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np) +static void arch_timer_detect_rate(void) { - /* Who has more than one independent system counter? */ - if (arch_timer_rate) - return; + /* + * Try to get the timer frequency from + * cntfrq_el0(system coprocessor register). + */ + if (!arch_timer_rate) + arch_timer_rate = arch_timer_get_cntfrq(); + + /* Check the timer frequency. */ + if (!arch_timer_rate) + pr_warn("frequency not available\n"); +} +static void arch_timer_mem_detect_rate(void __iomem *cntbase) +{ /* - * Try to determine the frequency from the device tree or CNTFRQ, - * if ACPI is enabled, get the frequency from CNTFRQ ONLY. + * Try to determine the frequency from + * CNTFRQ in memory-mapped timer. */ - if (!acpi_disabled || - of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) { - if (cntbase) - arch_timer_rate = readl_relaxed(cntbase + CNTFRQ); - else - arch_timer_rate = arch_timer_get_cntfrq(); - } + if (!arch_timer_rate) + arch_timer_rate = readl_relaxed(cntbase + CNTFRQ); /* Check the timer frequency. */ - if (arch_timer_rate == 0) + if (!arch_timer_rate) pr_warn("frequency not available\n"); } @@ -886,7 +890,9 @@ 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); + if (!arch_timer_rate && + of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) + arch_timer_detect_rate(); arch_timer_c3stop = !of_property_read_bool(np, "always-on"); @@ -994,7 +1000,14 @@ 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 CNTFRQ. + */ + if (!arch_timer_rate && + of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) + arch_timer_mem_detect_rate(base); + ret = arch_timer_mem_register(base, irq); if (ret) goto out; @@ -1056,7 +1069,7 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table) gtdt->non_secure_el2_flags); /* Get the frequency from CNTFRQ */ - arch_timer_detect_rate(NULL, NULL); + arch_timer_detect_rate(); arch_timer_uses_ppi = arch_timer_select_ppi(); if (!arch_timer_ppi[arch_timer_uses_ppi]) {