drm: Don't allow page flip to change pixel format

A page flip is not a mode set, changing the frame buffer pixel format
doesn't make sense and isn't handled by most drivers anyway. Disallow
it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 957fb70e8d0e..c577baec416f 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -3638,6 +3638,12 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
                 goto out;
         }
 
+        if (crtc->fb->pixel_format != fb->pixel_format) {
+                DRM_DEBUG_KMS("Page flip is not allowed to change frame buffer format.\n");
+                ret = -EINVAL;
+                goto out;
+        }
+
         if (page_flip->flags & DRM_MODE_PAGE_FLIP_EVENT) {
                 ret = -ENOMEM;
                 spin_lock_irqsave(&dev->event_lock, flags);