[RESEND PATCH 1/3] drm: Don't allow page flip to change pixel format

[Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>]

From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

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>
---
 drivers/gpu/drm/drm_crtc.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index dd64a06..ef247d5 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -3739,6 +3739,14 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
 		goto out;
 	}
 
+	if (crtc->fb->pixel_format != fb->pixel_format ||
+	    crtc->fb->bits_per_pixel != crtc->fb->bits_per_pixel ||
+	    crtc->fb->depth != fb->depth) {
+		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);
-- 
1.8.1.5