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From: Greg KH <gregkh@linuxfoundation.org>
To: Xu Yang <xu.yang_2@nxp.com>
Cc: laurent.pinchart@ideasonboard.com, dan.scally@ideasonboard.com,
	m.grzeschik@pengutronix.de, jun.li@nxp.com, imx@lists.linux.dev,
	linux-usb@vger.kernel.org
Subject: Re: [RESEND] usb: gadget: uvc: queue pump work in uvcg_video_enable()
Date: Wed, 14 Aug 2024 13:47:23 +0200	[thread overview]
Message-ID: <2024081405-sample-duckbill-ffec@gregkh> (raw)
In-Reply-To: <20240814112537.2608949-1-xu.yang_2@nxp.com>

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@vger.kernel.org
> Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
> ---
>  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?

thanks,

greg k-h


  reply	other threads:[~2024-08-14 11:47 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-08-14 11:25 [RESEND] usb: gadget: uvc: queue pump work in uvcg_video_enable() Xu Yang
2024-08-14 11:47 ` Greg KH [this message]
2024-08-14 13:48   ` Xu Yang
2024-08-14 14:10     ` Greg KH
2024-08-15  2:02       ` Xu Yang

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