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Message-ID: <Y452xN7BzTdYIEIM@pendragon.ideasonboard.com>
Date: Tue, 6 Dec 2022 00:55:00 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Ricardo Ribalda <ribalda@...omium.org>
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 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, 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.
How does it get reprobed then ? By unloading and reloading the driver
(or unbinding and rebinding the device through sysfs) ?
> > 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
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