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References: <20220920-resend-elgato-v3-0-57668054127f@chromium.org>
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From:   Ricardo Ribalda <ribalda@chromium.org>
Date:   Tue, 6 Dec 2022 00:09:24 +0100
Message-ID: <CANiDSCv=i=tOYK1HDrdPh0yxpPGtrtuHhAJz4c7MwMmzW2WhEw@mail.gmail.com>
Subject: Re: [PATCH v3] media: uvcvideo: Recover stalled ElGato devices
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
        Yunke Cao <yunkec@chromium.org>,
        Sergey Senozhatsky <senozhatsky@chromium.org>
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On Mon, 5 Dec 2022 at 23:55, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Ricardo,
>
> On Mon, Dec 05, 2022 at 11:45:43PM +0100, Ricardo Ribalda wrote:
> > On Mon, 5 Dec 2022 at 23:39, Laurent Pinchart wrote:
> > > On Mon, Dec 05, 2022 at 01:53:01PM +0100, Ricardo Ribalda wrote:
> > > > Elgato Cam Link 4k can be in a stalled state if the resolution of
> > > > the external source has changed while the firmware initializes.
> > > > Once in this state, the device is useless until it receives a
> > > > USB reset. It has even been observed that the stalled state will
> > > > continue even after unplugging the device.
> > >
> > > Why, =C3=B4, why :'-(
> > >
> > > > lsusb -v
> > > >
> > > > Bus 002 Device 002: ID 0fd9:0066 Elgato Systems GmbH Cam Link 4K
> > > > Device Descriptor:
> > > >   bLength                18
> > > >   bDescriptorType         1
> > > >   bcdUSB               3.00
> > > >   bDeviceClass          239 Miscellaneous Device
> > > >   bDeviceSubClass         2
> > > >   bDeviceProtocol         1 Interface Association
> > > >   bMaxPacketSize0         9
> > > >   idVendor           0x0fd9 Elgato Systems GmbH
> > > >   idProduct          0x0066
> > > >   bcdDevice            0.00
> > > >   iManufacturer           1 Elgato
> > > >   iProduct                2 Cam Link 4K
> > > >   iSerial                 4 0005AC52FE000
> > > >   bNumConfigurations      1
> > > >
> > > > Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> > > > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > > > ---
> > > > Recover stalled ElGato devices
> > > >
> > > > Just a resend of this hw fix.
> > > >
> > > > To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > > To: Mauro Carvalho Chehab <mchehab@kernel.org>
> > > > Cc: linux-media@vger.kernel.org
> > > > Cc: linux-kernel@vger.kernel.org
> > > > Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> > > > Cc: Yunke Cao <yunkec@chromium.org>
> > > > ---
> > > > Changes in v3:
> > > > - Add Reviewed-by: Sergey
> > > > - Improve identation (Thanks Sergey!)
> > > > - Link to v2: https://lore.kernel.org/r/20220920-resend-elgato-v2-0=
-06b48b3b486a@chromium.org
> > > >
> > > > Changes in v2:
> > > > - Remove info from lsusb
> > > > - Link to v1: https://lore.kernel.org/r/20220920-resend-elgato-v1-0=
-8672a2380e3d@chromium.org
> > > > ---
> > > >  drivers/media/usb/uvc/uvc_video.c | 23 +++++++++++++++++++----
> > > >  1 file changed, 19 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/=
uvc/uvc_video.c
> > > > index 170a008f4006..a8323cf0e9f9 100644
> > > > --- a/drivers/media/usb/uvc/uvc_video.c
> > > > +++ b/drivers/media/usb/uvc/uvc_video.c
> > > > @@ -129,12 +129,13 @@ int uvc_query_ctrl(struct uvc_device *dev, u8=
 query, u8 unit,
> > > >       return -EPIPE;
> > > >  }
> > > >
> > > > +static const struct usb_device_id elgato_cam_link_4k =3D {
> > > > +     USB_DEVICE(0x0fd9, 0x0066)
> > > > +};
> > > > +
> > > >  static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
> > > >       struct uvc_streaming_control *ctrl)
> > > >  {
> > > > -     static const struct usb_device_id elgato_cam_link_4k =3D {
> > > > -             USB_DEVICE(0x0fd9, 0x0066)
> > > > -     };
> > > >       struct uvc_format *format =3D NULL;
> > > >       struct uvc_frame *frame =3D NULL;
> > > >       unsigned int i;
> > > > @@ -297,7 +298,7 @@ static int uvc_get_video_ctrl(struct uvc_stream=
ing *stream,
> > > >               dev_err(&stream->intf->dev,
> > > >                       "Failed to query (%u) UVC %s control : %d (ex=
p. %u).\n",
> > > >                       query, probe ? "probe" : "commit", ret, size)=
;
> > > > -             ret =3D -EIO;
> > > > +             ret =3D (ret =3D=3D -EPROTO) ? -EPROTO : -EIO;
> > >
> > > This will change the error returned by VIDIOC_S_FMT and VIDIOC_TRY_FM=
T,
> > > but I don't think that will cause issues.
> > >
> > > >               goto out;
> > > >       }
> > > >
> > > > @@ -2121,6 +2122,20 @@ int uvc_video_init(struct uvc_streaming *str=
eam)
> > > >        * request on the probe control, as required by the UVC speci=
fication.
> > > >        */
> > > >       ret =3D uvc_get_video_ctrl(stream, probe, 1, UVC_GET_CUR);
> > > > +
> > > > +     /*
> > > > +      * Elgato Cam Link 4k can be in a stalled state if the resolu=
tion of
> > > > +      * the external source has changed while the firmware initial=
izes.
> > > > +      * Once in this state, the device is useless until it receive=
s a
> > > > +      * USB reset. It has even been observed that the stalled stat=
e will
> > > > +      * continue even after unplugging the device.
> > > > +      */
> > > > +     if (usb_match_one_id(stream->dev->intf, &elgato_cam_link_4k) =
&&
> > > > +         (ret =3D=3D -EPROTO)) {
> > >
> > > I'd swap the tests, as the second one is cheaper. You also don't need
> > > the inner parentheses.
> > >
> > > > +             usb_reset_device(stream->dev->udev);
> > > > +             dev_err(&stream->intf->dev, "Restarting Elgato Cam Li=
nk 4K\n");
> > >
> > > I would also swap those two lines, if an error occurs when resetting =
the
> > > device, it's good to have the "restarting" message printed first.
> > >
> > > If I understand this correctly, probe will still fail, and the user w=
ill
> > > have to unplug and replug the device to fix this, right ? If so I'd
> > > expand the error message, maybe something along those lines:
> >
> > I kind of recall that it was not needed to replug the device. Will
> > test on real hardware to confirm.
>
> How does it get reprobed then ? By unloading and reloading the driver
> (or unbinding and rebinding the device through sysfs) ?

Just went through the internal bug report. We were rebinding the
driver during the test.

Will add the "unplug-replug" message

Thanks!


>
> > >                 dev_err(&stream->intf->dev, "Elgato Cam Link 4K firmw=
are crash detected\n");
> > >                 dev_err(&stream->intf->dev, "Resetting the device, un=
plug and replug to recover\n");
> > >
> > > Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > >
> > > > +     }
> > > > +
> > > >       if (ret < 0)
> > > >               return ret;
> > > >
> > > >
> > > > ---
> > > > base-commit: 521a547ced6477c54b4b0cc206000406c221b4d6
> > > > change-id: 20220920-resend-elgato-a845482bdd02
>
> --
> Regards,
>
> Laurent Pinchart


--=20
Ricardo Ribalda