[PATCH resend] [media] uvcvideo: zero seq number when disabling stream

Hans Yang
2017-09-15T06:28:57Z

For bulk-based devices, when disabling the video stream,
in addition to issue CLEAR_FEATURE(HALT), it is better to set
alternate setting 0 as well or the sequnce number in host
side will probably not reset to zero.

Then in next time video stream start, the device will expect
host starts packet from 0 sequence number but host actually
continue the sequence number from last transaction and this
causes transaction errors.

This commit fixes this by adding set alternate setting 0 back
as what isoch-based devices do.

Below error message will also be eliminated for some devices:
uvcvideo: Non-zero status (-71) in video completion handler.

Signed-off-by: Hans Yang <hansy@nvidia.com>
---
drivers/media/usb/uvc/uvc_video.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index fb86d6af398d..ad80c2a6da6a 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -1862,10 +1862,9 @@ int uvc_video_enable(struct uvc_streaming *stream, int enable)

if (!enable) {
uvc_uninit_video(stream, 1);
- if (stream->intf->num_altsetting > 1) {
- usb_set_interface(stream->dev->udev,
+ usb_set_interface(stream->dev->udev,
stream->intfnum, 0);
- } else {
+ if (stream->intf->num_altsetting == 1) {
/* UVC doesn't specify how to inform a bulk-based device
* when the video stream is stopped. Windows sends a
* CLEAR_FEATURE(HALT) request to the video streaming
--
2.1.4