media: uvcvideo: Improve error logging in uvc_query_ctrl()

Standard use of the driver may result in error messages on the kernel
log. This can hide other more important messages, and alert
unnecessarily the user. Let's keep dev_err() for the important
occasions.

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 <hverkuil-cisco@xs4all.nl>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 503ef29..f35674f 100644 (file)
--- 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,