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Date: Mon, 5 Dec 2022 23:45:43 +0100
From: Ricardo Ribalda <ribalda@...omium.org>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
Yunke Cao <yunkec@...omium.org>,
Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: Re: [PATCH v3] media: uvcvideo: Recover stalled ElGato devices
Hi Laurent
Thanks for your review
On Mon, 5 Dec 2022 at 23:39, Laurent Pinchart
<laurent.pinchart@...asonboard.com> wrote:
>
> Hi Ricardo,
>
> Thank you for the patch.
>
> 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, รด, 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@...omium.org>
> > Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> > ---
> > Recover stalled ElGato devices
> >
> > Just a resend of this hw fix.
> >
> > To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> > To: Mauro Carvalho Chehab <mchehab@...nel.org>
> > Cc: linux-media@...r.kernel.org
> > Cc: linux-kernel@...r.kernel.org
> > Cc: Sergey Senozhatsky <senozhatsky@...omium.org>
> > Cc: Yunke Cao <yunkec@...omium.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 = {
> > + 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 = {
> > - USB_DEVICE(0x0fd9, 0x0066)
> > - };
> > struct uvc_format *format = NULL;
> > struct uvc_frame *frame = NULL;
> > unsigned int i;
> > @@ -297,7 +298,7 @@ static int uvc_get_video_ctrl(struct uvc_streaming *stream,
> > dev_err(&stream->intf->dev,
> > "Failed to query (%u) UVC %s control : %d (exp. %u).\n",
> > query, probe ? "probe" : "commit", ret, size);
> > - ret = -EIO;
> > + ret = (ret == -EPROTO) ? -EPROTO : -EIO;
>
> This will change the error returned by VIDIOC_S_FMT and VIDIOC_TRY_FMT,
> but I don't think that will cause issues.
>
> > goto out;
> > }
> >
> > @@ -2121,6 +2122,20 @@ int uvc_video_init(struct uvc_streaming *stream)
> > * request on the probe control, as required by the UVC specification.
> > */
> > ret = uvc_get_video_ctrl(stream, probe, 1, UVC_GET_CUR);
> > +
> > + /*
> > + * 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.
> > + */
> > + if (usb_match_one_id(stream->dev->intf, &elgato_cam_link_4k) &&
> > + (ret == -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 Link 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 will
> 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.
>
> dev_err(&stream->intf->dev, "Elgato Cam Link 4K firmware crash detected\n");
> dev_err(&stream->intf->dev, "Resetting the device, unplug and replug to recover\n");
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
>
> > + }
> > +
> > if (ret < 0)
> > return ret;
> >
> >
> > ---
> > base-commit: 521a547ced6477c54b4b0cc206000406c221b4d6
> > change-id: 20220920-resend-elgato-a845482bdd02
>
> --
> Regards,
>
> Laurent Pinchart
--
Ricardo Ribalda
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