media: ov772x: add checks for register read errors

This change adds checks for register read errors and returns correct
error code.

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/i2c/ov772x.c

@@ -1146,7 +1146,7 @@ static int ov772x_set_fmt(struct v4l2_subdev *sd,
 static int ov772x_video_probe(struct ov772x_priv *priv)
 {
 	struct i2c_client  *client = v4l2_get_subdevdata(&priv->subdev);
-	u8                  pid, ver;
+	int		    pid, ver, midh, midl;
 	const char         *devname;
 	int		    ret;
 
@@ -1156,7 +1156,11 @@ static int ov772x_video_probe(struct ov772x_priv *priv)
 
 	/* Check and show product ID and manufacturer ID. */
 	pid = ov772x_read(client, PID);
+	if (pid < 0)
+		return pid;
 	ver = ov772x_read(client, VER);
+	if (ver < 0)
+		return ver;
 
 	switch (VERSION(pid, ver)) {
 	case OV7720:
@@ -1172,13 +1176,17 @@ static int ov772x_video_probe(struct ov772x_priv *priv)
 		goto done;
 	}
 
+	midh = ov772x_read(client, MIDH);
+	if (midh < 0)
+		return midh;
+	midl = ov772x_read(client, MIDL);
+	if (midl < 0)
+		return midl;
+
 	dev_info(&client->dev,
 		 "%s Product ID %0x:%0x Manufacturer ID %x:%x\n",
-		 devname,
-		 pid,
-		 ver,
-		 ov772x_read(client, MIDH),
-		 ov772x_read(client, MIDL));
+		 devname, pid, ver, midh, midl);
+
 	ret = v4l2_ctrl_handler_setup(&priv->hdl);
 
 done: