[Intel-gfx] [PATCH v1 1/1] drm/i915: Perform modeset based on DPMS state during resume

[sagar.a.kamble at intel.com]

From: Akash Goel <akash.goel at intel.com>

During resume, modeset was being performed independent of DPMS state which
increased resume time as well as it kept display wells ON. With this change
this modeset will be skipped.

Signed-off-by: Akash Goel <akash.goel at intel.com>
Signed-off-by: Sagar Kamble <sagar.a.kamble at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c | 33 ++++++++++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 71be3c9..919e552 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -671,6 +671,31 @@ int i915_suspend_legacy(struct drm_device *dev, pm_message_t state)
 	return i915_drm_suspend_late(dev);
 }
 
+static bool display_is_on(struct drm_device *dev)
+{
+	struct drm_connector *connector;
+	bool display_is_on = false;
+
+	drm_modeset_lock_all(dev);
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+		if (!connector->encoder || !connector->encoder->crtc)
+			continue;
+		/*
+		 * If Display wasn't turned off, before going to suspend then
+		 * it should be re-enabled now, as we don't expect the DPMS ON
+		 * call to come in that case
+		 */
+		if (connector->dpms != DRM_MODE_DPMS_OFF) {
+			DRM_DEBUG_KMS("Display was on before suspend\n");
+			display_is_on = true;
+			break;
+		}
+	}
+	drm_modeset_unlock_all(dev);
+
+	return display_is_on;
+}
+
 static int i915_drm_resume(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -707,9 +732,11 @@ static int i915_drm_resume(struct drm_device *dev)
 		spin_unlock_irq(&dev_priv->irq_lock);
 
 		intel_dp_mst_resume(dev);
-		drm_modeset_lock_all(dev);
-		intel_modeset_setup_hw_state(dev, true);
-		drm_modeset_unlock_all(dev);
+		if (display_is_on(dev)) {
+			drm_modeset_lock_all(dev);
+			intel_modeset_setup_hw_state(dev, true);
+			drm_modeset_unlock_all(dev);
+		}
 
 		/*
 		 * ... but also need to make sure that hotplug processing
-- 
1.8.5