drm/atomic: Update legacy DPMS state during modesets, v3.

This is required for DPMS to work correctly, during a modeset
the DPMS property should be turned off, unless the state is
crtc is made active in which case it should be set to DPMS on.

Changes since v1:
- Set DPMS to off when a connector is removed from a crtc too.
- Update the legacy dpms property too.
- Add an exception for the legacy dpms paths, it updates its own state.
Changes since v2:
- Do not preserve dpms property.

Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_atomic_helper.c

@@ -660,15 +660,29 @@ drm_atomic_helper_update_legacy_modeset_state(struct drm_device *dev,
 	struct drm_crtc_state *old_crtc_state;
 	int i;
 
-	/* clear out existing links */
+	/* clear out existing links and update dpms */
 	for_each_connector_in_state(old_state, connector, old_conn_state, i) {
-		if (!connector->encoder)
-			continue;
+		if (connector->encoder) {
+			WARN_ON(!connector->encoder->crtc);
+
+			connector->encoder->crtc = NULL;
+			connector->encoder = NULL;
+		}
 
-		WARN_ON(!connector->encoder->crtc);
+		crtc = connector->state->crtc;
+		if ((!crtc && old_conn_state->crtc) ||
+		    (crtc && drm_atomic_crtc_needs_modeset(crtc->state))) {
+			struct drm_property *dpms_prop =
+				dev->mode_config.dpms_property;
+			int mode = DRM_MODE_DPMS_OFF;
 
-		connector->encoder->crtc = NULL;
-		connector->encoder = NULL;
+			if (crtc && crtc->state->active)
+				mode = DRM_MODE_DPMS_ON;
+
+			connector->dpms = mode;
+			drm_object_property_set_value(&connector->base,
+						      dpms_prop, mode);
+		}
 	}
 
 	/* set new links */

drivers/gpu/drm/i915/intel_display.c

@@ -12349,16 +12349,9 @@ intel_modeset_update_state(struct drm_atomic_state *state)
 			continue;
 
 		if (crtc->state->active) {
-			struct drm_property *dpms_property =
-				dev->mode_config.dpms_property;
-
-			connector->dpms = DRM_MODE_DPMS_ON;
-			drm_object_property_set_value(&connector->base, dpms_property, DRM_MODE_DPMS_ON);
-
 			intel_encoder = to_intel_encoder(connector->encoder);
 			intel_encoder->connectors_active = true;
-		} else
-			connector->dpms = DRM_MODE_DPMS_OFF;
+		}
 	}
 }