drm: rcar-du: Improve kernel log messages when initializing encoders

Improve the debugging and error messages printing when initializing
encoders by replacing the output number by the output name, printing the
bridge OF node name, and the error code of failed operations.

While at it, move the related rcar_du_output enumeration from
rcar_du_crtc.h to rcar_du_drv.h as it's not specific to the CRTC.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

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

@@ -93,17 +93,6 @@ struct rcar_du_crtc_state {
 
 #define to_rcar_crtc_state(s) container_of(s, struct rcar_du_crtc_state, state)
 
-enum rcar_du_output {
-	RCAR_DU_OUTPUT_DPAD0,
-	RCAR_DU_OUTPUT_DPAD1,
-	RCAR_DU_OUTPUT_LVDS0,
-	RCAR_DU_OUTPUT_LVDS1,
-	RCAR_DU_OUTPUT_HDMI0,
-	RCAR_DU_OUTPUT_HDMI1,
-	RCAR_DU_OUTPUT_TCON,
-	RCAR_DU_OUTPUT_MAX,
-};
-
 int rcar_du_crtc_create(struct rcar_du_group *rgrp, unsigned int swindex,
 			unsigned int hwindex);
 

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

@@ -502,6 +502,24 @@ static const struct of_device_id rcar_du_of_table[] = {
 
 MODULE_DEVICE_TABLE(of, rcar_du_of_table);
 
+const char *rcar_du_output_name(enum rcar_du_output output)
+{
+	static const char * const names[] = {
+		[RCAR_DU_OUTPUT_DPAD0] = "DPAD0",
+		[RCAR_DU_OUTPUT_DPAD1] = "DPAD1",
+		[RCAR_DU_OUTPUT_LVDS0] = "LVDS0",
+		[RCAR_DU_OUTPUT_LVDS1] = "LVDS1",
+		[RCAR_DU_OUTPUT_HDMI0] = "HDMI0",
+		[RCAR_DU_OUTPUT_HDMI1] = "HDMI1",
+		[RCAR_DU_OUTPUT_TCON] = "TCON",
+	};
+
+	if (output >= ARRAY_SIZE(names) || !names[output])
+		return "UNKNOWN";
+
+	return names[output];
+}
+
 /* -----------------------------------------------------------------------------
  * DRM operations
  */

drivers/gpu/drm/rcar-du/rcar_du_drv.h

@@ -33,6 +33,17 @@ struct rcar_du_device;
 
 #define RCAR_DU_QUIRK_ALIGN_128B	BIT(0)	/* Align pitches to 128 bytes */
 
+enum rcar_du_output {
+	RCAR_DU_OUTPUT_DPAD0,
+	RCAR_DU_OUTPUT_DPAD1,
+	RCAR_DU_OUTPUT_LVDS0,
+	RCAR_DU_OUTPUT_LVDS1,
+	RCAR_DU_OUTPUT_HDMI0,
+	RCAR_DU_OUTPUT_HDMI1,
+	RCAR_DU_OUTPUT_TCON,
+	RCAR_DU_OUTPUT_MAX,
+};
+
 /*
  * struct rcar_du_output_routing - Output routing specification
  * @possible_crtcs: bitmask of possible CRTCs for the output
@@ -126,4 +137,6 @@ static inline void rcar_du_write(struct rcar_du_device *rcdu, u32 reg, u32 data)
 	iowrite32(data, rcdu->mmio + reg);
 }
 
+const char *rcar_du_output_name(enum rcar_du_output output);
+
 #endif /* __RCAR_DU_DRV_H__ */

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

@@ -103,8 +103,8 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
 			return -ENOLINK;
 	}
 
-	dev_dbg(rcdu->dev, "initializing encoder %pOF for output %u\n",
-		enc_node, output);
+	dev_dbg(rcdu->dev, "initializing encoder %pOF for output %s\n",
+		enc_node, rcar_du_output_name(output));
 
 	renc = drmm_encoder_alloc(&rcdu->ddev, struct rcar_du_encoder, base,
 				  &rcar_du_encoder_funcs, DRM_MODE_ENCODER_NONE,
@@ -118,8 +118,9 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
 	ret = drm_bridge_attach(&renc->base, bridge, NULL,
 				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 	if (ret) {
-		dev_err(rcdu->dev, "failed to attach bridge for output %u\n",
-			output);
+		dev_err(rcdu->dev,
+			"failed to attach bridge %pOF for output %s (%d)\n",
+			bridge->of_node, rcar_du_output_name(output), ret);
 		return ret;
 	}
 
@@ -127,7 +128,8 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
 	connector = drm_bridge_connector_init(&rcdu->ddev, &renc->base);
 	if (IS_ERR(connector)) {
 		dev_err(rcdu->dev,
-			"failed to created connector for output %u\n", output);
+			"failed to created connector for output %s (%ld)\n",
+			rcar_du_output_name(output), PTR_ERR(connector));
 		return PTR_ERR(connector);
 	}
 

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

@@ -513,8 +513,8 @@ static int rcar_du_encoders_init_one(struct rcar_du_device *rcdu,
 	ret = rcar_du_encoder_init(rcdu, output, entity);
 	if (ret && ret != -EPROBE_DEFER && ret != -ENOLINK)
 		dev_warn(rcdu->dev,
-			 "failed to initialize encoder %pOF on output %u (%d), skipping\n",
-			 entity, output, ret);
+			 "failed to initialize encoder %pOF on output %s (%d), skipping\n",
+			 entity, rcar_du_output_name(output), ret);
 
 	of_node_put(entity);