drm: Check CRTC compatibility in setplane

The DRM core setplane code should check that the plane is usable on the
specified CRTC before calling into the driver.

Prior to this patch, a plane's possible_crtcs field was purely
informational for userspace and was never actually verified at the
kernel level (aside from the primary plane helper).

Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Chon Ming Lee <chon.ming.lee@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_crtc.c

@@ -2178,6 +2178,13 @@ int drm_mode_setplane(struct drm_device *dev, void *data,
 		goto out;
 	}
 
+	/* Check whether this plane is usable on this CRTC */
+	if (!(plane->possible_crtcs & drm_crtc_mask(crtc))) {
+		DRM_DEBUG_KMS("Invalid crtc for plane\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
 	fb = drm_framebuffer_lookup(dev, plane_req->fb_id);
 	if (!fb) {
 		DRM_DEBUG_KMS("Unknown framebuffer ID %d\n",

drivers/gpu/drm/drm_plane_helper.c

@@ -145,12 +145,6 @@ int drm_primary_helper_update(struct drm_plane *plane, struct drm_crtc *crtc,
 		return -EINVAL;
 	}
 
-	/* Primary planes are locked to their owning CRTC */
-	if (plane->possible_crtcs != drm_crtc_mask(crtc)) {
-		DRM_DEBUG_KMS("Cannot change primary plane CRTC\n");
-		return -EINVAL;
-	}
-
 	/* Disallow scaling */
 	src_w >>= 16;
 	src_h >>= 16;