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From:   Ricardo Ribalda <ribalda@chromium.org>
Date:   Fri, 18 Nov 2022 10:12:05 +0100
Message-ID: <CANiDSCs2y6zOu09sxU60NX7se-N=wq3Z6USQz+XckQt7rC=3xg@mail.gmail.com>
Subject: Re: Re: [PATCH v3] media: uvcvideo: Fix bandwidth error for Alcor camera
To:     =?UTF-8?B?6Im+6LaF?= <aichao@kylinos.cn>
Cc:     laurent.pinchart@ideasonboard.com, mchehab@kernel.org,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
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Hi Ai

On Fri, 18 Nov 2022 at 10:09, =E8=89=BE=E8=B6=85 <aichao@kylinos.cn> wrote:
>
> Hi Ricardo
>
>
> > 3072 is smaller than 0x1000.
> > It is ok to have values between 1024 and 0x1000 (4096) ?

Wouldn't it make more sense ?
  ctrl->dwMaxPayloadTransferSize =3D 0x1000;


The value 1000 seems a bit random, specially when your compare your
range with 4096
>
>
> Yes,  for some new device which requested 3072 B/frame bandwidth,  that t=
he camera preview normally.
>
>
>
>
> ----
>
>
>
>
>
>
> =E4=B8=BB=E3=80=80=E9=A2=98=EF=BC=9ARe: [PATCH v3] media: uvcvideo: Fix b=
andwidth error for Alcor camera
> =E6=97=A5=E3=80=80=E6=9C=9F=EF=BC=9A2022-11-18 16:15
> =E5=8F=91=E4=BB=B6=E4=BA=BA=EF=BC=9Aribalda@chromium.org
> =E6=94=B6=E4=BB=B6=E4=BA=BA=EF=BC=9A=E8=89=BE=E8=B6=85
>
>
> Hi Ai
>
> Thanks for your patch!
>
> On Fri, 18 Nov 2022 at 03:23, Ai Chao <aichao@kylinos.cn> wrote:
> >
> > For Alcor Corp. Slave camera(1b17:6684/2017:0011), it support to
> > output compressed video data, and it return a wrong
> > dwMaxPayloadTransferSize fields. This is a fireware issue,
> s/fireware/firmware/
> > but the manufacturer cannot provide a const return fields
> > by the fireware. For some device, device requested 2752512
> >  B/frame bandwidth. For some device, device requested 3072
> >  B/frame bandwidth. so we check the dwMaxPayloadTransferSize
> >  fields,if it large than 0x1000, reset dwMaxPayloadTransferSize
> > to 1024, and the camera preview normally.
>
> 3072 is smaller than 0x1000.
>
> It is ok to have values between 1024 and 0x1000 (4096) ?
>
> Thanks
>
> >
> > Signed-off-by: Ai Chao <aichao@kylinos.cn>
> >
> > ---
> > change for v3
> > - Add VID/PID 2017:0011
> >
> > change for v2
> > - Used usb_match_one_id to check VID and PID
> > ---
> > ---
> >  drivers/media/usb/uvc/uvc_video.c | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/=
uvc_video.c
> > index d2eb9066e4dc..1260800ef8bd 100644
> > --- a/drivers/media/usb/uvc/uvc_video.c
> > +++ b/drivers/media/usb/uvc/uvc_video.c
> > @@ -135,6 +135,10 @@ static void uvc_fixup_video_ctrl(struct uvc_stream=
ing *stream,
> >         static const struct usb_device_id elgato_cam_link_4k =3D {
> >                 USB_DEVICE(0x0fd9, 0x0066)
> >         };
> > +       static const struct usb_device_id alcor_corp_slave_cam =3D {
> > +               USB_DEVICE(0x1b17, 0x6684),
> > +               USB_DEVICE(0x2017, 0x0011),
> > +       };
> >         struct uvc_format *format =3D NULL;
> >         struct uvc_frame *frame =3D NULL;
> >         unsigned int i;
> > @@ -234,6 +238,13 @@ static void uvc_fixup_video_ctrl(struct uvc_stream=
ing *stream,
> >
> >                 ctrl->dwMaxPayloadTransferSize =3D bandwidth;
> >         }
> > +
> > +       /* Alcor Corp. Slave camera return wrong dwMaxPayloadTransferSi=
ze */
> > +       if ((format->flags & UVC_FMT_FLAG_COMPRESSED) &&
> > +           (ctrl->dwMaxPayloadTransferSize > 0x1000) &&
> > +            usb_match_one_id(stream->dev->intf, &alcor_corp_slave_cam)=
) {
> > +               ctrl->dwMaxPayloadTransferSize =3D 1024;
> > +       }
> >  }
> >
> >  static size_t uvc_video_ctrl_size(struct uvc_streaming *stream)
> > --
> > 2.25.1
> >
>
>
> --
> Ricardo Ribalda


--=20
Ricardo Ribalda