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authorAbhilash Jindal <klock.android@gmail.com>2015-08-11 12:01:22 -0400
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2015-09-01 15:51:43 +0200
commit72e624de6e6f0d5a638fbc23842aa76ae048e9e7 (patch)
tree5752040aa7d5293ce0aa33a122f9900aa1f0fb63 /drivers/cpufreq/speedstep-lib.c
parent309d0631cc329ca1051c631c89e0acc9b752cb4d (diff)
downloadleg-kernel-72e624de6e6f0d5a638fbc23842aa76ae048e9e7.tar.gz
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>
Diffstat (limited to 'drivers/cpufreq/speedstep-lib.c')
-rw-r--r--drivers/cpufreq/speedstep-lib.c9
1 files changed, 4 insertions, 5 deletions
diff --git a/drivers/cpufreq/speedstep-lib.c b/drivers/cpufreq/speedstep-lib.c
index 4ab7a2156672..15d3214aaa00 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 */