drm: Share plane pixel format check code between legacy and atomic

Both the legacy and atomic helpers need to check whether a plane
supports a given pixel format. The code is currently duplicated, share
it.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
[danvet: Slightly extend the docbook.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_atomic.c

@@ -475,7 +475,7 @@ static int drm_atomic_plane_check(struct drm_plane *plane,
 		struct drm_plane_state *state)
 {
 	unsigned int fb_width, fb_height;
-	unsigned int i;
+	int ret;
 
 	/* either *both* CRTC and FB must be set, or neither */
 	if (WARN_ON(state->crtc && !state->fb)) {
@@ -497,13 +497,11 @@ static int drm_atomic_plane_check(struct drm_plane *plane,
 	}
 
 	/* Check whether this plane supports the fb pixel format. */
-	for (i = 0; i < plane->format_count; i++)
-		if (state->fb->pixel_format == plane->format_types[i])
-			break;
-	if (i == plane->format_count) {
+	ret = drm_plane_check_pixel_format(plane, state->fb->pixel_format);
+	if (ret) {
 		DRM_DEBUG_ATOMIC("Invalid pixel format %s\n",
 				 drm_get_format_name(state->fb->pixel_format));
-		return -EINVAL;
+		return ret;
 	}
 
 	/* Give drivers some help against integer overflows */

drivers/gpu/drm/drm_crtc.c

@@ -2408,6 +2408,27 @@ int drm_mode_getplane(struct drm_device *dev, void *data,
 	return 0;
 }
 
+/**
+ * drm_plane_check_pixel_format - Check if the plane supports the pixel format
+ * @plane: plane to check for format support
+ * @format: the pixel format
+ *
+ * Returns:
+ * Zero of @plane has @format in its list of supported pixel formats, -EINVAL
+ * otherwise.
+ */
+int drm_plane_check_pixel_format(const struct drm_plane *plane, u32 format)
+{
+	unsigned int i;
+
+	for (i = 0; i < plane->format_count; i++) {
+		if (format == plane->format_types[i])
+			return 0;
+	}
+
+	return -EINVAL;
+}
+
 /*
  * setplane_internal - setplane handler for internal callers
  *
@@ -2428,7 +2449,6 @@ static int __setplane_internal(struct drm_plane *plane,
 {
 	int ret = 0;
 	unsigned int fb_width, fb_height;
-	unsigned int i;
 
 	/* No fb means shut it down */
 	if (!fb) {
@@ -2451,13 +2471,10 @@ static int __setplane_internal(struct drm_plane *plane,
 	}
 
 	/* Check whether this plane supports the fb pixel format. */
-	for (i = 0; i < plane->format_count; i++)
-		if (fb->pixel_format == plane->format_types[i])
-			break;
-	if (i == plane->format_count) {
+	ret = drm_plane_check_pixel_format(plane, fb->pixel_format);
+	if (ret) {
 		DRM_DEBUG_KMS("Invalid pixel format %s\n",
 			      drm_get_format_name(fb->pixel_format));
-		ret = -EINVAL;
 		goto out;
 	}
 

include/drm/drm_crtc.h

@@ -1263,6 +1263,8 @@ extern int drm_plane_init(struct drm_device *dev,
 extern void drm_plane_cleanup(struct drm_plane *plane);
 extern unsigned int drm_plane_index(struct drm_plane *plane);
 extern void drm_plane_force_disable(struct drm_plane *plane);
+extern int drm_plane_check_pixel_format(const struct drm_plane *plane,
+					u32 format);
 extern void drm_crtc_get_hv_timing(const struct drm_display_mode *mode,
 				   int *hdisplay, int *vdisplay);
 extern int drm_crtc_check_viewport(const struct drm_crtc *crtc,