drm/rcar-du/crc: Implement verify_crc_source callback

This patch implements "verify_crc_source" callback function for
rcar drm driver.

Changes Since V1:
 - avoid duplication of code
Changes Since V2:
 - further optimize the code
Changes Since V3:
 - Adopt to driver style
 - Address review comments from Laurent Pinchart

Signed-off-by: Mahesh Kumar <mahesh1.kumar@intel.com>
Cc: dri-devel@lists.freedesktop.org
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180723103824.21734-1-mahesh1.kumar@intel.com

drivers/gpu/drm/rcar-du/rcar_du_crtc.c

@@ -756,17 +756,11 @@ static void rcar_du_crtc_disable_vblank(struct drm_crtc *crtc)
 	rcrtc->vblank_enable = false;
 }
 
-static int rcar_du_crtc_set_crc_source(struct drm_crtc *crtc,
-				       const char *source_name,
-				       size_t *values_cnt)
+static int rcar_du_crtc_parse_crc_source(struct rcar_du_crtc *rcrtc,
+					 const char *source_name,
+					 enum vsp1_du_crc_source *source)
 {
-	struct rcar_du_crtc *rcrtc = to_rcar_crtc(crtc);
-	struct drm_modeset_acquire_ctx ctx;
-	struct drm_crtc_state *crtc_state;
-	struct drm_atomic_state *state;
-	enum vsp1_du_crc_source source;
-	unsigned int index = 0;
-	unsigned int i;
+	unsigned int index;
 	int ret;
 
 	/*
@@ -774,30 +768,64 @@ static int rcar_du_crtc_set_crc_source(struct drm_crtc *crtc,
 	 * CRC on an input plane (%u is the plane ID), and "auto" to compute the
 	 * CRC on the composer (VSP) output.
 	 */
+
 	if (!source_name) {
-		source = VSP1_DU_CRC_NONE;
+		*source = VSP1_DU_CRC_NONE;
+		return 0;
 	} else if (!strcmp(source_name, "auto")) {
-		source = VSP1_DU_CRC_OUTPUT;
+		*source = VSP1_DU_CRC_OUTPUT;
+		return 0;
 	} else if (strstarts(source_name, "plane")) {
-		source = VSP1_DU_CRC_PLANE;
+		unsigned int i;
+
+		*source = VSP1_DU_CRC_PLANE;
 
 		ret = kstrtouint(source_name + strlen("plane"), 10, &index);
 		if (ret < 0)
 			return ret;
 
 		for (i = 0; i < rcrtc->vsp->num_planes; ++i) {
-			if (index == rcrtc->vsp->planes[i].plane.base.id) {
-				index = i;
-				break;
-			}
+			if (index == rcrtc->vsp->planes[i].plane.base.id)
+				return i;
 		}
+	}
 
-		if (i >= rcrtc->vsp->num_planes)
-			return -EINVAL;
-	} else {
+	return -EINVAL;
+}
+
+static int rcar_du_crtc_verify_crc_source(struct drm_crtc *crtc,
+					  const char *source_name,
+					  size_t *values_cnt)
+{
+	struct rcar_du_crtc *rcrtc = to_rcar_crtc(crtc);
+	enum vsp1_du_crc_source source;
+
+	if (rcar_du_crtc_parse_crc_source(rcrtc, source_name, &source) < 0) {
+		DRM_DEBUG_DRIVER("unknown source %s\n", source_name);
 		return -EINVAL;
 	}
 
+	*values_cnt = 1;
+	return 0;
+}
+
+static int rcar_du_crtc_set_crc_source(struct drm_crtc *crtc,
+				       const char *source_name,
+				       size_t *values_cnt)
+{
+	struct rcar_du_crtc *rcrtc = to_rcar_crtc(crtc);
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_crtc_state *crtc_state;
+	struct drm_atomic_state *state;
+	enum vsp1_du_crc_source source;
+	unsigned int index;
+	int ret;
+
+	ret = rcar_du_crtc_parse_crc_source(rcrtc, source_name, &source);
+	if (ret < 0)
+		return ret;
+
+	index = ret;
 	*values_cnt = 1;
 
 	/* Perform an atomic commit to set the CRC source. */
@@ -861,6 +889,7 @@ static const struct drm_crtc_funcs crtc_funcs_gen3 = {
 	.enable_vblank = rcar_du_crtc_enable_vblank,
 	.disable_vblank = rcar_du_crtc_disable_vblank,
 	.set_crc_source = rcar_du_crtc_set_crc_source,
+	.verify_crc_source = rcar_du_crtc_verify_crc_source,
 };
 
 /* -----------------------------------------------------------------------------