[Intel-gfx] [PATCH 15/14] drm/i915: Add comments explaining the vdd on/off functions

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

Jani wanted some comments to explain why we call certain vdd on/off
functions in certain places.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 1067082..1233a10 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1315,6 +1315,7 @@ static  u32 ironlake_get_pp_control(struct intel_dp *intel_dp)
 	return control;
 }
 
+/* should be paired with edp_panel_vdd_off() */
 static bool edp_panel_vdd_on(struct intel_dp *intel_dp)
 {
 	struct drm_device *dev = intel_dp_to_dev(intel_dp);
@@ -1365,6 +1366,7 @@ static bool edp_panel_vdd_on(struct intel_dp *intel_dp)
 	return need_to_disable;
 }
 
+/* should be paired with intel_edp_panel_vdd_off() */
 void intel_edp_panel_vdd_on(struct intel_dp *intel_dp)
 {
 	struct drm_i915_private *dev_priv =
@@ -1447,6 +1449,7 @@ static void edp_panel_vdd_schedule_off(struct intel_dp *intel_dp)
 	schedule_delayed_work(&intel_dp->panel_vdd_work, delay);
 }
 
+/* should be paired with edp_panel_vdd_on() */
 static void edp_panel_vdd_off(struct intel_dp *intel_dp, bool sync)
 {
 	struct drm_i915_private *dev_priv =
@@ -1467,6 +1470,7 @@ static void edp_panel_vdd_off(struct intel_dp *intel_dp, bool sync)
 		edp_panel_vdd_schedule_off(intel_dp);
 }
 
+/* should be paired with intel_edp_panel_vdd_on() */
 static void intel_edp_panel_vdd_off(struct intel_dp *intel_dp, bool sync)
 {
 	struct drm_i915_private *dev_priv =
@@ -4307,6 +4311,10 @@ void intel_dp_encoder_destroy(struct drm_encoder *encoder)
 	drm_encoder_cleanup(encoder);
 	if (is_edp(intel_dp)) {
 		cancel_delayed_work_sync(&intel_dp->panel_vdd_work);
+		/*
+		 * vdd might still be enabled do to the delayed vdd off.
+		 * Make sure vdd is actually turned off here.
+		 */
 		mutex_lock(&dev_priv->pps_mutex);
 		edp_panel_vdd_off_sync(intel_dp);
 		mutex_unlock(&dev_priv->pps_mutex);
@@ -4327,6 +4335,10 @@ static void intel_dp_encoder_suspend(struct intel_encoder *intel_encoder)
 	if (!is_edp(intel_dp))
 		return;
 
+	/*
+	 * vdd might still be enabled do to the delayed vdd off.
+	 * Make sure vdd is actually turned off here.
+	 */
 	mutex_lock(&dev_priv->pps_mutex);
 	edp_panel_vdd_off_sync(intel_dp);
 	mutex_unlock(&dev_priv->pps_mutex);
@@ -5025,6 +5037,10 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 		drm_dp_aux_unregister(&intel_dp->aux);
 		if (is_edp(intel_dp)) {
 			cancel_delayed_work_sync(&intel_dp->panel_vdd_work);
+			/*
+			 * vdd might still be enabled do to the delayed vdd off.
+			 * Make sure vdd is actually turned off here.
+			 */
 			mutex_lock(&dev_priv->pps_mutex);
 			edp_panel_vdd_off_sync(intel_dp);
 			mutex_unlock(&dev_priv->pps_mutex);
-- 
1.8.5.5