Hi Roger, Thank you for the patch. On Friday 03 Mar 2017 13:17:15 Roger Quadros wrote: > On alternate setting change, webcam gadget sends us a UVC_EVENT_STREAMON > or UVC_EVENT_STREAMOFF event. It expects delayed status response on > STREAMON event only but doesn't expect us to send that response over USB. > It sends the delayed response when we issue the VIDIOC_STREAMON ioctl. > > So we must not send UVCIOC_SEND_RESPONSE ioctl in these cases that too > with invalid response length. The commit message only explains why we should not call UVCIOC_SEND_RESPONSE in response to a STREAMON event, but not why we shouldn't either in response to a STREAMOFF event. The patch is correct changing both, but I propose wording the above two paragraphs as follows. "uvc-gadget: Do not send Set Interface (alternate setting) response twice On alternate setting change, the webcam gadget sends us a UVC_EVENT_STREAMON or UVC_EVENT_STREAMOFF event. In the first case, the driver will issue a delayed status response automatically when we call the VIDIOC_STREAMON ioctl. In the second case, the driver sends the status response immediately. We must thus not send the status response manually with UVCIOC_SEND_RESPONSE in any of those cases." If you're fine with that I'll change the message when applying, there's no need to resend the patch. > Without this, the ISO streaming doesn't work if host application > (e.g. luvcview) is closed and restarted. > On dwc3 gadget controller it was resulting in Buffer Expiry error on > the ISO endpoint. > > Signed-off-by: Roger Quadros <rogerq@xxxxxx> > --- > uvc-gadget.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/uvc-gadget.c b/uvc-gadget.c > index 9ef315c..4d59ab8 100644 > --- a/uvc-gadget.c > +++ b/uvc-gadget.c > @@ -597,12 +597,12 @@ uvc_events_process(struct uvc_device *dev) > case UVC_EVENT_STREAMON: > uvc_video_reqbufs(dev, 4); > uvc_video_stream(dev, 1); > - break; > + return; > > case UVC_EVENT_STREAMOFF: > uvc_video_stream(dev, 0); > uvc_video_reqbufs(dev, 0); > - break; > + return; > } > > ioctl(dev->fd, UVCIOC_SEND_RESPONSE, &resp); -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
