amd/display: set backlight only if required

From Shirish S
a551e6629247dc84f8cea5d494542c532ea69161 in linux 5.15.y/5.15.34
4052287a75eb3fc0f487fcc5f768a38bede455c8 in mainline linux

diff --git a/sys/dev/pci/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/sys/dev/pci/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 6620de3..6d36599 100644 (file)
--- a/sys/dev/pci/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/sys/dev/pci/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -3524,7 +3524,7 @@ static u32 convert_brightness_to_user(const struct amdgpu_dm_backlight_caps *cap
                                 max - min);
 }
 
-static int amdgpu_dm_backlight_set_level(struct amdgpu_display_manager *dm,
+static void amdgpu_dm_backlight_set_level(struct amdgpu_display_manager *dm,
                                         int bl_idx,
                                         u32 user_brightness)
 {
@@ -3552,7 +3552,8 @@ static int amdgpu_dm_backlight_set_level(struct amdgpu_display_manager *dm,
                        DRM_DEBUG("DM: Failed to update backlight on eDP[%d]\n", bl_idx);
        }
 
-       return rc ? 0 : 1;
+       if (rc)
+               dm->actual_brightness[bl_idx] = user_brightness;
 }
 
 static int amdgpu_dm_backlight_update_status(struct backlight_device *bd)
@@ -9330,7 +9331,7 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
        /* restore the backlight level */
        for (i = 0; i < dm->num_of_edps; i++) {
                if (dm->backlight_dev[i] &&
-                   (amdgpu_dm_backlight_get_level(dm, i) != dm->brightness[i]))
+                   (dm->actual_brightness[i] != dm->brightness[i]))
                        amdgpu_dm_backlight_set_level(dm, i, dm->brightness[i]);
        }
 #endif

diff --git a/sys/dev/pci/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/sys/dev/pci/drm/amd/display/amdgpu_dm/amdgpu_dm.h
index 1f304a7..391d1dc 100644 (file)
--- a/sys/dev/pci/drm/amd/display/amdgpu_dm/amdgpu_dm.h
+++ b/sys/dev/pci/drm/amd/display/amdgpu_dm/amdgpu_dm.h
@@ -446,6 +446,12 @@ struct amdgpu_display_manager {
         * cached backlight values.
         */
        u32 brightness[AMDGPU_DM_MAX_NUM_EDP];
+       /**
+        * @actual_brightness:
+        *
+        * last successfully applied backlight values.
+        */
+       u32 actual_brightness[AMDGPU_DM_MAX_NUM_EDP];
 };
 
 enum dsc_clock_force_state {