From: Hans Verkuil <hverkuil-cisco@xs4all.nl>

If __uvc_query_ctrl() failed with a non-EPIPE error, then
report that with dev_err. If an error code is obtained, then
report that with dev_dbg.

Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 170a008f4006..2cf7f692c0bb 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -79,13 +79,14 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit,
 	if (likely(ret == size))
 		return 0;
 
-	dev_err(&dev->udev->dev,
-		"Failed to query (%s) UVC control %u on unit %u: %d (exp. %u).\n",
-		uvc_query_name(query), cs, unit, ret, size);
-
-	if (ret != -EPIPE)
+	if (ret != -EPIPE) {
+		dev_err(&dev->udev->dev,
+			"Failed to query (%s) UVC control %u on unit %u: %d (exp. %u).\n",
+			uvc_query_name(query), cs, unit, ret, size);
 		return ret;
+	}
 
+	/* reuse data[0] to request the error code. */
 	tmp = *(u8 *)data;
 
 	ret = __uvc_query_ctrl(dev, UVC_GET_CUR, 0, intfnum,

-- 
b4 0.11.0-dev-d93f8