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>

2 files changed, 7 insertions, 6 deletions

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 43735f38cd17..b8cc4fe0a0f7 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/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",
diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c
index 1b15643b4586..37b9333cee49 100644
--- a/drivers/gpu/drm/drm_plane_helper.c
+++ b/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;