drm: Print bad user modes

Print out the modeline when we reject a bad user mode. Avoids having to
guess why it was rejected.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180611193403.16118-2-ville.syrjala@linux.intel.com
Reviewed-by: Harry Wentland <harry.wentland@amd.com>

drivers/gpu/drm/drm_atomic.c

@@ -392,10 +392,24 @@ int drm_atomic_set_mode_prop_for_crtc(struct drm_crtc_state *state,
 	memset(&state->mode, 0, sizeof(state->mode));
 
 	if (blob) {
-		if (blob->length != sizeof(struct drm_mode_modeinfo) ||
-		    drm_mode_convert_umode(state->crtc->dev, &state->mode,
-					   blob->data))
+		int ret;
+
+		if (blob->length != sizeof(struct drm_mode_modeinfo)) {
+			DRM_DEBUG_ATOMIC("[CRTC:%d:%s] bad mode blob length: %zu\n",
+					 crtc->base.id, crtc->name,
+					 blob->length);
+			return -EINVAL;
+		}
+
+		ret = drm_mode_convert_umode(crtc->dev,
+					     &state->mode, blob->data);
+		if (ret) {
+			DRM_DEBUG_ATOMIC("[CRTC:%d:%s] invalid mode (ret=%d, status=%s):\n",
+					 crtc->base.id, crtc->name,
+					 ret, drm_get_mode_status_name(state->mode.status));
+			drm_mode_debug_printmodeline(&state->mode);
 			return -EINVAL;
+		}
 
 		state->mode_blob = drm_property_blob_get(blob);
 		state->enable = true;

drivers/gpu/drm/drm_crtc.c

@@ -649,7 +649,9 @@ retry:
 
 		ret = drm_mode_convert_umode(dev, mode, &crtc_req->mode);
 		if (ret) {
-			DRM_DEBUG_KMS("Invalid mode\n");
+			DRM_DEBUG_KMS("Invalid mode (ret=%d, status=%s)\n",
+				      ret, drm_get_mode_status_name(mode->status));
+			drm_mode_debug_printmodeline(mode);
 			goto out;
 		}
 

drivers/gpu/drm/drm_crtc_internal.h

@@ -56,6 +56,9 @@ int drm_mode_setcrtc(struct drm_device *dev,
 int drm_modeset_register_all(struct drm_device *dev);
 void drm_modeset_unregister_all(struct drm_device *dev);
 
+/* drm_modes.c */
+const char *drm_get_mode_status_name(enum drm_mode_status status);
+
 /* IOCTLs */
 int drm_mode_getresources(struct drm_device *dev,
 			  void *data, struct drm_file *file_priv);

drivers/gpu/drm/drm_modes.c

@@ -1257,7 +1257,7 @@ static const char * const drm_mode_status_names[] = {
 
 #undef MODE_STATUS
 
-static const char *drm_get_mode_status_name(enum drm_mode_status status)
+const char *drm_get_mode_status_name(enum drm_mode_status status)
 {
 	int index = status + 3;