On Wed, Aug 14, 2024 at 01:47:23PM +0200, Greg KH wrote:
> On Wed, Aug 14, 2024 at 07:25:37PM +0800, Xu Yang wrote:
> > Since commit "6acba0345b68 usb:gadget:uvc Do not use worker thread to pump
> > isoc usb requests", pump work could only be queued in uvc_video_complete()
> > and uvc_v4l2_qbuf(). If VIDIOC_QBUF is executed before VIDIOC_STREAMON,
> > we can only depend on uvc_video_complete() to queue pump work. However,
> > this requires some free requests in req_ready list. If req_ready list is
> > empty all the time, pump work will never be queued and video datas will
> > never be pumped to usb controller. Actually, this situation could happen
> > when run uvc-gadget with static image:
> >
> > $ ./uvc-gadget -i 1080p.jpg uvc.0
> >
> > When capture image from this device, the user app will always block there.
> >
> > The issue is uvc driver has queued video buffer before streamon, but the
> > req_ready list is empty all the time after streamon. This will queue pump
> > work in uvcg_video_enable() to fill some request to req_ready list so the
> > uvc device could work properly.
> >
> > Fixes: 6acba0345b68 ("usb:gadget:uvc Do not use worker thread to pump isoc usb requests")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Xu Yang <xu.yang_2@xxxxxxx>
> > ---
> > drivers/usb/gadget/function/uvc_video.c | 1 +
> > 1 file changed, 1 insertion(+)
>
> Why is this a RESEND? What happened to the first one to require this?
I accidentally forgot to cc usb maillist in previous one. So I resend it.
Thanks,
Xu Yang
>
> thanks,
>
> greg k-h
>
