Some cameras, like the ELMO MX-P3, do not return all the bytes requested from a control if it can fit in less bytes. Eg: Returning 0xab instead of 0x00ab. usb 3-9: Failed to query (GET_DEF) UVC control 3 on unit 2: 1 (exp. 2).
Extend the returned value from the camera and return it.
Cc: stable@vger.kernel.org Fixes: a763b9fb58be ("media: uvcvideo: Do not return positive errors in uvc_query_ctrl()") Reviewed-by: Hans de Goede hdegoede@redhat.com Signed-off-by: Ricardo Ribalda ribalda@chromium.org --- drivers/media/usb/uvc/uvc_video.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index cd9c29532fb0..482c4ceceaac 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -79,6 +79,22 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit, if (likely(ret == size)) return 0;
+ /* + * In UVC the data is usually represented in little-endian. + * Some devices return shorter USB control packets that expected if the + * returned value can fit in less bytes. Zero all the bytes that the + * device have not written. + * We exclude UVC_GET_INFO from the quirk. UVC_GET_LEN does not need to + * be excluded because its size is always 1. + */ + if (ret > 0 && query != UVC_GET_INFO) { + memset(data + ret, 0, size - ret); + dev_warn_once(&dev->udev->dev, + "UVC non compliance: %s control %u on unit %u returned %d bytes when we expected %u.\n", + uvc_query_name(query), cs, unit, ret, size); + return 0; + } + if (ret != -EPIPE) { dev_err(&dev->udev->dev, "Failed to query (%s) UVC control %u on unit %u: %d (exp. %u).\n",