[PATCH] cpufreq: speedstep-lib: Use monotonic clock
From: Abhilash Jindal <hidden>
Date: 2015-08-11 16:01:26
Subsystem:
cpu frequency scaling framework, the rest · Maintainers:
"Rafael J. Wysocki", Viresh Kumar, Linus Torvalds
Wall time obtained from do_gettimeofday is susceptible to sudden jumps due to user setting the time or due to NTP. Monotonic time is constantly increasing time better suited for comparing two timestamps. Signed-off-by: Abhilash Jindal <redacted> --- drivers/cpufreq/speedstep-lib.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/drivers/cpufreq/speedstep-lib.c b/drivers/cpufreq/speedstep-lib.c
index 4ab7a21..15d3214 100644
--- a/drivers/cpufreq/speedstep-lib.c
+++ b/drivers/cpufreq/speedstep-lib.c@@ -386,7 +386,7 @@ unsigned int speedstep_get_freqs(enum speedstep_processor processor, unsigned int prev_speed; unsigned int ret = 0; unsigned long flags; - struct timeval tv1, tv2; + ktime_t tv1, tv2; if ((!processor) || (!low_speed) || (!high_speed) || (!set_state)) return -EINVAL;
@@ -415,14 +415,14 @@ unsigned int speedstep_get_freqs(enum speedstep_processor processor, /* start latency measurement */ if (transition_latency) - do_gettimeofday(&tv1); + tv1 = ktime_get(); /* switch to high state */ set_state(SPEEDSTEP_HIGH); /* end latency measurement */ if (transition_latency) - do_gettimeofday(&tv2); + tv2 = ktime_get(); *high_speed = speedstep_get_frequency(processor); if (!*high_speed) {
@@ -442,8 +442,7 @@ unsigned int speedstep_get_freqs(enum speedstep_processor processor, set_state(SPEEDSTEP_LOW); if (transition_latency) { - *transition_latency = (tv2.tv_sec - tv1.tv_sec) * USEC_PER_SEC + - tv2.tv_usec - tv1.tv_usec; + *transition_latency = ktime_to_us(ktime_sub(tv2, tv1)); pr_debug("transition latency is %u uSec\n", *transition_latency); /* convert uSec to nSec and add 20% for safety reasons */
--
1.7.9.5