devfreq: don't set last_scale for same freq

In nvhost_pod_estimate_freq(), we have *freq = 0
in case we decide to keep same frequency
In that case we set *freq as current frequency and
then set last_scale timestamp

This can result in keeping same frequency for
long duration due to less delta from last_scale

To fix this, return immediately in case *freq
is zero and do not set last_scale timestamp

Bug 200255163

Change-Id: Ie13bf54e2415c4016a101b9ea12a9abda83240fd
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/1265185
Reviewed-on: http://git-master/r/1506359
(cherry picked from linux-4.9 commit be5331c94ebe9044cb67e3f622db517bfb7e28d4)
Reviewed-on: https://git-master.nvidia.com/r/1770149
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Timo Alho <talho@nvidia.com>
Tested-by: Timo Alho <talho@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/devfreq/governor_pod_scaling.c b/drivers/devfreq/governor_pod_scaling.c
index 1849a85f9..d7250a176 100644
--- a/drivers/devfreq/governor_pod_scaling.c
+++ b/drivers/devfreq/governor_pod_scaling.c
@@ -669,8 +669,10 @@ static int nvhost_pod_estimate_freq(struct devfreq *df,
                         msecs_to_jiffies(podgov->p_slowdown_delay));
         }
 
-        if (!(*freq))
+        if (!(*freq)) {
                 *freq = dev_stat.current_frequency;
+                return 0;
+        }
 
         if (freqlist_up(podgov, *freq, 0) == dev_stat.current_frequency)
                 return 0;