linux-kernel - Re:Re: [PATCH v10] media: uvcvideo: Fix bandwidth issue for Alcor camera.

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Message-ID: <3b644a8c.9fa7.196d399cac8.Coremail.ccc194101@163.com>
Date: Thu, 15 May 2025 18:59:53 +0800 (CST)
From: 自己 <ccc194101@....com>
To: "Laurent Pinchart" <laurent.pinchart@...asonboard.com>
Cc: "Ricardo Ribalda" <ribalda@...omium.org>, hdegoede@...hat.com,
	mchehab@...nel.org, linux-kernel@...r.kernel.org,
	linux-media@...r.kernel.org,
	chenchangcheng <chenchangcheng@...inos.cn>
Subject: Re:Re: [PATCH v10] media: uvcvideo: Fix bandwidth issue for Alcor
 camera.

Dear Ricardo Ribalda & Laurent Pinchart:


At 2025-05-15 16:12:02, "Laurent Pinchart" <laurent.pinchart@...asonboard.com> wrote:
>On Wed, May 14, 2025 at 11:17:06AM +0200, Ricardo Ribalda wrote:
>> Hi chenchangcheng
>> 
>> Thanks for your patience fixing the warnings from media-ci :)
>> 
>> Regards
>> 
>> On Sat, 10 May 2025 at 08:18, chenchangcheng <ccc194101@....com> wrote:
>> >
>> > From: chenchangcheng <chenchangcheng@...inos.cn>
>> >
>> > Some broken device return wrong dwMaxPayloadTransferSize fields
>> > as follows:
>> >     [  218.632537] [pid:20427,cpu6,guvcview,8]uvcvideo: Device requested 2752512 B/frame bandwidth.
>> >     [  218.632598] [pid:20427,cpu6,guvcview,9]uvcvideo: No fast enough alt setting for requested bandwidth.
>> >
>> > When dwMaxPayloadTransferSize is greater than maxpsize,
>> > it will prevent the camera from starting.
>> > So use the bandwidth of maxpsize.
>> >
>> > Signed-off-by: chenchangcheng <chenchangcheng@...inos.cn>
>
>> Reviewed-by: Ricardo Ribalda <ribalda@...omium.org>
>>
>> > ---
>> >  drivers/media/usb/uvc/uvc_video.c | 9 +++++++++
>> >  1 file changed, 9 insertions(+)
>> >
>> > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
>> > index e3567aeb0007..a74cf89852d1 100644
>> > --- a/drivers/media/usb/uvc/uvc_video.c
>> > +++ b/drivers/media/usb/uvc/uvc_video.c
>> > @@ -262,6 +262,15 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
>> >
>> >                 ctrl->dwMaxPayloadTransferSize = bandwidth;
>> >         }
>> > +
>> > +       if (stream->intf->num_altsetting > 1 &&
>> > +           ctrl->dwMaxPayloadTransferSize > stream->maxpsize) {
>> > +               dev_warn_ratelimited(&stream->intf->dev,
>> > +                                    "the max payload transmission size (%d) exceededs the size of the ep max packet (%d). Using the max size.\n",
>> > +                                    ctrl->dwMaxPayloadTransferSize,
>> 
>> Minor nitpick. I am trying to standarize "UVC non compliance" header
>> in the logs for this kind of things.
>> 
>> "UVC non compliance: the max payload transmission size (%d) exceededs
>> the size of the ep max packet (%d). Using the max size.\n"
>
>s/exceededs/exceeds/
>
>I will also replauce %d with %u as both variables are unsigned.
>
>Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
>
>> > +                                    stream->maxpsize);
>> > +               ctrl->dwMaxPayloadTransferSize = stream->maxpsize;
>> > +       }
>> >  }
>> >
>> >  static size_t uvc_video_ctrl_size(struct uvc_streaming *stream)
>> >
>> > base-commit: d76bb1ebb5587f66b0f8b8099bfbb44722bc08b3
>
>-- 
>Regards,
>
>Laurent Pinchart


      Thank you for your guidance.
      I will submit a new version after the modifications.

-- 
Regards,

Changcheng Chen