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);elsearch_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.