[PATCH] PM / Domains: Skip latency measurements if timekeeping is suspended
From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: 2015-03-18 16:25:56
Also in:
linux-pm, lkml
Subsystem:
driver core, kobjects, debugfs and sysfs, hibernation (aka software suspend, aka swsusp), power management core, suspend to ram, the rest · Maintainers:
Greg Kroah-Hartman, "Rafael J. Wysocki", Danilo Krummrich, Linus Torvalds
The PM Domain code uses ktime_get() to perform various latency
measurements. However, if ktime_get() is called while timekeeping is
suspended, the following warning is printed:
WARNING: CPU: 0 PID: 1340 at kernel/time/timekeeping.c:576 ktime_get+0x30/0xf4()
This happens when resuming the PM Domain that contains the clock events
source. Chain of operations is:
timekeeping_resume()
{
clockevents_resume()
sh_cmt_clock_event_resume()
pm_genpd_syscore_poweron()
pm_genpd_sync_poweron()
genpd_power_on()
ktime_get(), but timekeeping_suspended = 1
...
timekeeping_suspended = 0;
}
Skip all latency measurements if timekeeping is suspended to fix this.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
I'm not sure if this is needed for all latency measurements.
So far I only encountered it while powering-on a clock domain during
resume from s2ram.
---
drivers/base/power/domain.c | 39 +++++++++++++++++++++++++++++----------
1 file changed, 29 insertions(+), 10 deletions(-)
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 45937f88e77c8889..ab2398cfcebb7732 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c@@ -18,6 +18,7 @@ #include <linux/sched.h> #include <linux/suspend.h> #include <linux/export.h> +#include <linux/timekeeping.h> #define GENPD_DEV_CALLBACK(genpd, type, callback, dev) \ ({ \
@@ -33,16 +34,24 @@ #define GENPD_DEV_TIMED_CALLBACK(genpd, type, callback, dev, field, name) \ ({ \ - ktime_t __start = ktime_get(); \ - type __retval = GENPD_DEV_CALLBACK(genpd, type, callback, dev); \ - s64 __elapsed = ktime_to_ns(ktime_sub(ktime_get(), __start)); \ - struct gpd_timing_data *__td = &dev_gpd_data(dev)->td; \ - if (!__retval && __elapsed > __td->field) { \ - __td->field = __elapsed; \ - dev_dbg(dev, name " latency exceeded, new value %lld ns\n", \ - __elapsed); \ - genpd->max_off_time_changed = true; \ - __td->constraint_changed = true; \ + type __retval; \ + if (unlikely(timekeeping_suspended)) { \ + dev_dbg(dev, "Skipping %s timings\n", #callback); \ + __retval = GENPD_DEV_CALLBACK(genpd, type, callback, dev); \ + } else { \ + ktime_t __start = ktime_get(); \ + type __ret = GENPD_DEV_CALLBACK(genpd, type, callback, dev); \ + s64 __elapsed = ktime_to_ns(ktime_sub(ktime_get(), __start)); \ + struct gpd_timing_data *__td = &dev_gpd_data(dev)->td; \ + if (!__ret && __elapsed > __td->field) { \ + __td->field = __elapsed; \ + dev_dbg(dev, \ + name " latency exceeded, new value %lld ns\n", \ + __elapsed); \ + genpd->max_off_time_changed = true; \ + __td->constraint_changed = true; \ + } \ + __retval = __ret; \ } \ __retval; \ })
@@ -161,6 +170,11 @@ static int genpd_power_on(struct generic_pm_domain *genpd) if (!genpd->power_on) return 0; + if (unlikely(timekeeping_suspended)) { + pr_debug("%s: Skipping %s timings\n", genpd->name, "power_on"); + return genpd->power_on(genpd); + } + time_start = ktime_get(); ret = genpd->power_on(genpd); if (ret)
@@ -188,6 +202,11 @@ static int genpd_power_off(struct generic_pm_domain *genpd) if (!genpd->power_off) return 0; + if (unlikely(timekeeping_suspended)) { + pr_debug("%s: Skipping %s timings\n", genpd->name, "power_off"); + return genpd->power_off(genpd); + } + time_start = ktime_get(); ret = genpd->power_off(genpd); if (ret = -EBUSY)
--
1.9.1