cpufreq: speedstep-lib: Use monotonic clock
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 <klock.android@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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 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 @@
/* 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 @@
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 */