devfreq: set current freq in case no change required

API scaling_state_check() returns 0 in case no change
in frequency is required
In nvhost_pod_estimate_freq(), we set *freq to 0
in case scaling_state_check() returns 0

And as a result of this, update_devfreq() will just
keep setting minimum frequency instead of keeping
same frequency - and this results in huge
performance degradation

To fix this, set *freq to current frequency in case
scaling_state_check() returns 0 as estimated
frequency

Bug 200255163

Change-Id: Ia8fe54dfd48b0898cc1dd53d821b1c95865b1f57
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/1261281
(cherry picked from linux-4.9 commit 624718566201ce9c0b9780be6f29dc2ae9082b09)
Reviewed-on: https://git-master.nvidia.com/r/1770146
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, 4 insertions, 2 deletions

diff --git a/drivers/devfreq/governor_pod_scaling.c b/drivers/devfreq/governor_pod_scaling.c
index 3ffaeb78d..cca369997 100644
--- a/drivers/devfreq/governor_pod_scaling.c
+++ b/drivers/devfreq/governor_pod_scaling.c
@@ -799,8 +799,10 @@ static int nvhost_pod_estimate_freq(struct devfreq *df,
                         msecs_to_jiffies(podgov->p_slowdown_delay));
         }
 
-        if (!(*freq) ||
-            (freqlist_up(podgov, *freq, 0) == dev_stat.current_frequency))
+        if (!(*freq))
+                *freq = dev_stat.current_frequency;
+
+        if (freqlist_up(podgov, *freq, 0) == dev_stat.current_frequency)
                 return 0;
 
         podgov->last_scale = now;