drm/atomic-helper: Add option to update planes only on active crtc

With drivers supporting runtime pm it's generally not a good idea to
touch the hardware when it's off. Add an option to the commit_planes
helper to support this case.

Note that the helpers already add all planes on a crtc when a modeset
happens, hence plane updates will not be lost if drivers set this to
true.

v2: Check for NULL state->crtc before chasing the pointer. Also check
both old and new crtc if there's a switch. Finally just outright
disallow switching crtcs for a plane if the plane is in active use, on
most hardware that doesn't make sense.

v3: Since commit_planes(active_only = true) is for enabling things
only after all the crtc are on we should only look at the new crtc to
decide whether to call the plane hooks - if the current CRTC isn't on
then skip. If the old crtc (when moving a plane) went down then the
plane should have been disabled as part of the pipe shutdown work
already. For which there's currently no helper really unfortunately.
Also move the check for wether a plane gets a new CRTC assigned while
still in active use out of this patch.

v4: Rebase over exynos changes.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Thierry Reding <treding@nvidia.com>
Cc: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Tested-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

drivers/gpu/drm/drm_atomic_helper.c

@@ -1037,7 +1037,7 @@ int drm_atomic_helper_commit(struct drm_device *dev,
 
 	drm_atomic_helper_commit_modeset_disables(dev, state);
 
-	drm_atomic_helper_commit_planes(dev, state);
+	drm_atomic_helper_commit_planes(dev, state, false);
 
 	drm_atomic_helper_commit_modeset_enables(dev, state);
 
@@ -1146,10 +1146,16 @@ int drm_atomic_helper_prepare_planes(struct drm_device *dev,
 }
 EXPORT_SYMBOL(drm_atomic_helper_prepare_planes);
 
+bool plane_crtc_active(struct drm_plane_state *state)
+{
+	return state->crtc && state->crtc->state->active;
+}
+
 /**
  * drm_atomic_helper_commit_planes - commit plane state
  * @dev: DRM device
  * @old_state: atomic state object with old state structures
+ * @active_only: Only commit on active CRTC if set
  *
  * This function commits the new plane state using the plane and atomic helper
  * functions for planes and crtcs. It assumes that the atomic state has already
@@ -1164,7 +1170,8 @@ EXPORT_SYMBOL(drm_atomic_helper_prepare_planes);
  * drm_atomic_helper_commit_planes_on_crtc() instead.
  */
 void drm_atomic_helper_commit_planes(struct drm_device *dev,
-				     struct drm_atomic_state *old_state)
+				     struct drm_atomic_state *old_state,
+				     bool active_only)
 {
 	struct drm_crtc *crtc;
 	struct drm_crtc_state *old_crtc_state;
@@ -1180,6 +1187,9 @@ void drm_atomic_helper_commit_planes(struct drm_device *dev,
 		if (!funcs || !funcs->atomic_begin)
 			continue;
 
+		if (active_only && !crtc->state->active)
+			continue;
+
 		funcs->atomic_begin(crtc, old_crtc_state);
 	}
 
@@ -1191,6 +1201,9 @@ void drm_atomic_helper_commit_planes(struct drm_device *dev,
 		if (!funcs)
 			continue;
 
+		if (active_only && !plane_crtc_active(plane->state))
+			continue;
+
 		/*
 		 * Special-case disabling the plane if drivers support it.
 		 */
@@ -1210,6 +1223,9 @@ void drm_atomic_helper_commit_planes(struct drm_device *dev,
 		if (!funcs || !funcs->atomic_flush)
 			continue;
 
+		if (active_only && !crtc->state->active)
+			continue;
+
 		funcs->atomic_flush(crtc, old_crtc_state);
 	}
 }

drivers/gpu/drm/exynos/exynos_drm_drv.c

@@ -105,7 +105,7 @@ static void exynos_atomic_commit_complete(struct exynos_atomic_commit *commit)
 		atomic_inc(&exynos_crtc->pending_update);
 	}
 
-	drm_atomic_helper_commit_planes(dev, state);
+	drm_atomic_helper_commit_planes(dev, state, false);
 
 	exynos_atomic_wait_for_commit(state);
 

drivers/gpu/drm/msm/msm_atomic.c

@@ -125,7 +125,7 @@ static void complete_commit(struct msm_commit *c)
 
 	drm_atomic_helper_commit_modeset_disables(dev, state);
 
-	drm_atomic_helper_commit_planes(dev, state);
+	drm_atomic_helper_commit_planes(dev, state, false);
 
 	drm_atomic_helper_commit_modeset_enables(dev, state);
 

drivers/gpu/drm/omapdrm/omap_drv.c

@@ -96,7 +96,7 @@ static void omap_atomic_complete(struct omap_atomic_state_commit *commit)
 	dispc_runtime_get();
 
 	drm_atomic_helper_commit_modeset_disables(dev, old_state);
-	drm_atomic_helper_commit_planes(dev, old_state);
+	drm_atomic_helper_commit_planes(dev, old_state, false);
 	drm_atomic_helper_commit_modeset_enables(dev, old_state);
 
 	omap_atomic_wait_for_completion(dev, old_state);

drivers/gpu/drm/rcar-du/rcar_du_kms.c

@@ -456,7 +456,7 @@ static void rcar_du_atomic_complete(struct rcar_du_commit *commit)
 	/* Apply the atomic update. */
 	drm_atomic_helper_commit_modeset_disables(dev, old_state);
 	drm_atomic_helper_commit_modeset_enables(dev, old_state);
-	drm_atomic_helper_commit_planes(dev, old_state);
+	drm_atomic_helper_commit_planes(dev, old_state, false);
 
 	drm_atomic_helper_wait_for_vblanks(dev, old_state);
 

drivers/gpu/drm/sti/sti_drv.c

@@ -59,7 +59,7 @@ static void sti_atomic_complete(struct sti_private *private,
 	 */
 
 	drm_atomic_helper_commit_modeset_disables(drm, state);
-	drm_atomic_helper_commit_planes(drm, state);
+	drm_atomic_helper_commit_planes(drm, state, false);
 	drm_atomic_helper_commit_modeset_enables(drm, state);
 
 	drm_atomic_helper_wait_for_vblanks(drm, state);

drivers/gpu/drm/tegra/drm.c

@@ -56,7 +56,7 @@ static void tegra_atomic_complete(struct tegra_drm *tegra,
 	 */
 
 	drm_atomic_helper_commit_modeset_disables(drm, state);
-	drm_atomic_helper_commit_planes(drm, state);
+	drm_atomic_helper_commit_planes(drm, state, false);
 	drm_atomic_helper_commit_modeset_enables(drm, state);
 
 	drm_atomic_helper_wait_for_vblanks(drm, state);

include/drm/drm_atomic_helper.h

@@ -55,7 +55,8 @@ void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
 int drm_atomic_helper_prepare_planes(struct drm_device *dev,
 				     struct drm_atomic_state *state);
 void drm_atomic_helper_commit_planes(struct drm_device *dev,
-				     struct drm_atomic_state *state);
+				     struct drm_atomic_state *state,
+				     bool active_only);
 void drm_atomic_helper_cleanup_planes(struct drm_device *dev,
 				      struct drm_atomic_state *old_state);
 void drm_atomic_helper_commit_planes_on_crtc(struct drm_crtc_state *old_crtc_state);