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+rene...@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
--
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