media: v4l: subdev: Print debug information on frame descriptor

Print debug level information on returned frame descriptors.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

drivers/media/v4l2-core/v4l2-subdev.c

@@ -15,6 +15,7 @@
 #include <linux/module.h>
 #include <linux/overflow.h>
 #include <linux/slab.h>
+#include <linux/string.h>
 #include <linux/types.h>
 #include <linux/version.h>
 #include <linux/videodev2.h>
@@ -309,9 +310,37 @@ static int call_set_selection(struct v4l2_subdev *sd,
 static int call_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
 			       struct v4l2_mbus_frame_desc *fd)
 {
+	unsigned int i;
+	int ret;
+
 	memset(fd, 0, sizeof(*fd));
 
-	return sd->ops->pad->get_frame_desc(sd, pad, fd);
+	ret = sd->ops->pad->get_frame_desc(sd, pad, fd);
+	if (ret)
+		return ret;
+
+	dev_dbg(sd->dev, "Frame descriptor on pad %u, type %s\n", pad,
+		fd->type == V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL ? "parallel" :
+		fd->type == V4L2_MBUS_FRAME_DESC_TYPE_CSI2 ? "CSI-2" :
+		"unknown");
+
+	for (i = 0; i < fd->num_entries; i++) {
+		struct v4l2_mbus_frame_desc_entry *entry = &fd->entry[i];
+		char buf[20] = "";
+
+		if (fd->type == V4L2_MBUS_FRAME_DESC_TYPE_CSI2)
+			WARN_ON(snprintf(buf, sizeof(buf),
+					 ", vc %u, dt 0x%02x",
+					 entry->bus.csi2.vc,
+					 entry->bus.csi2.dt) >= sizeof(buf));
+
+		dev_dbg(sd->dev,
+			"\tstream %u, code 0x%04x, length %u, flags 0x%04x%s\n",
+			entry->stream, entry->pixelcode, entry->length,
+			entry->flags, buf);
+	}
+
+	return 0;
 }
 
 static inline int check_edid(struct v4l2_subdev *sd,