media: renesas: vsp1: Print debug message to diagnose validation failure

When formats don't match between a subdev and a connected video device,
starting streaming returns an error without giving the user any
indication as to what went wrong. To help debugging pipeline
misconfigurations, add a debug message that indicates the cause of the
failure.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>

drivers/media/platform/renesas/vsp1/vsp1_video.c

@@ -78,8 +78,14 @@ static int vsp1_video_verify_format(struct vsp1_video *video)
 
 	if (video->rwpf->fmtinfo->mbus != fmt.format.code ||
 	    video->rwpf->format.height != fmt.format.height ||
-	    video->rwpf->format.width != fmt.format.width)
-		return -EINVAL;
+	    video->rwpf->format.width != fmt.format.width) {
+		dev_dbg(video->vsp1->dev,
+			"Format mismatch: 0x%04x/%ux%u != 0x%04x/%ux%u\n",
+			video->rwpf->fmtinfo->mbus, video->rwpf->format.width,
+			video->rwpf->format.height, fmt.format.code,
+			fmt.format.width, fmt.format.height);
+		return -EPIPE;
+	}
 
 	return 0;
 }