devfreq: stop podgov polling when disabled through sysfs

The pod governor allows scaling to be enabled/disabled through
sysfs. In the current implementation the devfreq_monitor keeps polling
periodically even when scaling is disabled. This patch disables the
timer when scaling is disabled.

NVGPU-20

Change-Id: I6842585afec48dbc9a2fe5aee96867c68612a127
Signed-off-by: Peter Boonstoppel <pboonstoppel@nvidia.com>
Reviewed-on: https://git-master/r/1485185
(cherry picked from linux-4.9 commit 96ebb9e97b84092a852274f90e214d3976944b78)
Reviewed-on: https://git-master.nvidia.com/r/1770152
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, 46 insertions, 29 deletions

diff --git a/drivers/devfreq/governor_pod_scaling.c b/drivers/devfreq/governor_pod_scaling.c
index d7a470957..8f596cb02 100644
--- a/drivers/devfreq/governor_pod_scaling.c
+++ b/drivers/devfreq/governor_pod_scaling.c
@@ -84,6 +84,8 @@ struct podgov_info_rec {
         struct kobj_attribute   enable_3d_scaling_attr;
         struct kobj_attribute   user_attr;
         struct kobj_attribute   freq_request_attr;
+
+        struct mutex            lock;
 };
 
 /*******************************************************************************
@@ -127,42 +129,50 @@ static void scaling_limit(struct devfreq *df, unsigned long *freq)
 static void podgov_enable(struct devfreq *df, int enable)
 {
         struct device *dev = df->dev.parent;
-        struct podgov_info_rec *podgov;
+        struct podgov_info_rec *podgov = df->data;
+        bool polling;
 
         /* make sure the device is alive before doing any scaling */
         pm_runtime_get_noresume(dev);
 
+        mutex_lock(&podgov->lock);
         mutex_lock(&df->lock);
 
-        podgov = df->data;
-
         trace_podgov_enabled(df->dev.parent, enable);
 
         /* bad configuration. quit. */
-        if (df->min_freq == df->max_freq)
-                goto exit_unlock;
+        if (df->min_freq == df->max_freq) {
+                mutex_unlock(&df->lock);
+                mutex_unlock(&podgov->lock);
+                pm_runtime_put(dev);
+                return;
+        }
 
         /* store the enable information */
         podgov->enable = enable;
 
         /* skip local adjustment if we are enabling or the device is
          * suspended */
-        if (enable || !pm_runtime_active(dev))
-                goto exit_unlock;
+        if (!enable && pm_runtime_active(dev)) {
+                /* full speed */
+                podgov->adjustment_frequency = df->max_freq;
+                podgov->adjustment_type = ADJUSTMENT_LOCAL;
+                update_devfreq(df);
+        }
 
-        /* full speed */
-        podgov->adjustment_frequency = df->max_freq;
-        podgov->adjustment_type = ADJUSTMENT_LOCAL;
-        update_devfreq(df);
+        polling = podgov->enable && !podgov->p_user;
 
+        /* Need to unlock to call devfreq_monitor_suspend/resume()
+         * still holding podgov->lock to guarantee atomicity
+         */
         mutex_unlock(&df->lock);
 
-        pm_runtime_put(dev);
-
-        return;
+        if (polling)
+                devfreq_monitor_resume(df);
+        else
+                devfreq_monitor_suspend(df);
 
-exit_unlock:
-        mutex_unlock(&df->lock);
+        mutex_unlock(&podgov->lock);
         pm_runtime_put(dev);
 }
 
@@ -177,14 +187,15 @@ exit_unlock:
 static void podgov_set_user_ctl(struct devfreq *df, int user)
 {
         struct device *dev = df->dev.parent;
-        struct podgov_info_rec *podgov;
+        struct podgov_info_rec *podgov = df->data;
         int old_user;
+        bool polling;
 
         /* make sure the device is alive before doing any scaling */
         pm_runtime_get_noresume(dev);
 
+        mutex_lock(&podgov->lock);
         mutex_lock(&df->lock);
-        podgov = df->data;
 
         trace_podgov_set_user_ctl(df->dev.parent, user);
 
@@ -194,22 +205,26 @@ static void podgov_set_user_ctl(struct devfreq *df, int user)
 
         /* skip scaling, if scaling (or the whole device) is turned off
          * - or the scaling already was in user mode */
-        if (!pm_runtime_active(dev) || !podgov->enable ||
-            !(user && !old_user))
-                goto exit_unlock;
+        if (pm_runtime_active(dev) && podgov->enable && user && !old_user) {
+                /* write request */
+                podgov->adjustment_frequency = podgov->p_freq_request;
+                podgov->adjustment_type = ADJUSTMENT_LOCAL;
+                update_devfreq(df);
+        }
 
-        /* write request */
-        podgov->adjustment_frequency = podgov->p_freq_request;
-        podgov->adjustment_type = ADJUSTMENT_LOCAL;
-        update_devfreq(df);
+        polling = podgov->enable && !podgov->p_user;
 
+        /* Need to unlock to call devfreq_monitor_suspend/resume()
+         * still holding podgov->lock to guarantee atomicity
+         */
         mutex_unlock(&df->lock);
-        pm_runtime_put(dev);
 
-        return;
+        if (polling)
+                devfreq_monitor_resume(df);
+        else
+                devfreq_monitor_suspend(df);
 
-exit_unlock:
-        mutex_unlock(&df->lock);
+        mutex_unlock(&podgov->lock);
         pm_runtime_put(dev);
 }
 
@@ -622,6 +637,8 @@ static int nvhost_pod_init(struct devfreq *df)
 
         podgov->power_manager = df;
 
+        mutex_init(&podgov->lock);
+
         attr = &podgov->enable_3d_scaling_attr;
         attr->attr.name = "enable_3d_scaling";
         attr->attr.mode = S_IWUSR | S_IRUGO;