[PATCH 1/2] drm: mxsfb: Fix format changes for primary plane

[Laurent Pinchart]

The primary plane's format is configured in registers that have no
shadow support for live updates. They require the display to be fully
reconfigured in order to be updated. Force a mode set when the primary
plane format changes to ensure this.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 drivers/gpu/drm/mxsfb/mxsfb_kms.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
index 6d512f346918..7a69d9f3a875 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
@@ -407,14 +407,28 @@ static int mxsfb_plane_atomic_check(struct drm_plane *plane,
 {
 	struct mxsfb_drm_private *mxsfb = to_mxsfb_drm_private(plane->dev);
 	struct drm_crtc_state *crtc_state;
+	int ret;
 
 	crtc_state = drm_atomic_get_new_crtc_state(plane_state->state,
 						   &mxsfb->crtc);
 
-	return drm_atomic_helper_check_plane_state(plane_state, crtc_state,
-						   DRM_PLANE_HELPER_NO_SCALING,
-						   DRM_PLANE_HELPER_NO_SCALING,
-						   false, true);
+	ret = drm_atomic_helper_check_plane_state(plane_state, crtc_state,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  false, true);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Changing the primary plane format requires stopping the display
+	 * controller first. Force a full mode set to do so.
+	 */
+	if (plane == mxsfb->crtc.primary &&
+	    plane_state->visible && plane->state->visible &&
+	    plane_state->fb->format != plane->state->fb->format)
+		crtc_state->mode_changed = true;
+
+	return 0;
 }
 
 static void mxsfb_plane_primary_atomic_update(struct drm_plane *plane,
-- 
Regards,

Laurent Pinchart