[PATCH v2] media: uvcvideo: Recover stalled ElGato devices

From: Ricardo Ribalda
Date: Fri Dec 02 2022 - 12:01:37 EST


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.

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

Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
---
Recover stalled ElGato devices

Just a resend of this hw fix.

To: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
To: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
Cc: linux-media@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: Yunke Cao <yunkec@xxxxxxxxxxxx>
---
Changes in v2:
- Remove info from lsusb
- Link to v1: https://lore.kernel.org/r/20220920-resend-elgato-v1-0-8672a2380e3d@xxxxxxxxxxxx
---
drivers/media/usb/uvc/uvc_video.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 170a008f4006..ad1762b66c4c 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -129,12 +129,12 @@ 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 +297,7 @@ 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;
goto out;
}

@@ -2121,6 +2121,20 @@ 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)) {
+ usb_reset_device(stream->dev->udev);
+ dev_err(&stream->intf->dev, "Restarting Elgato Cam Link 4K\n");
+ }
+
if (ret < 0)
return ret;


---
base-commit: 521a547ced6477c54b4b0cc206000406c221b4d6
change-id: 20220920-resend-elgato-a845482bdd02

Best regards,
--
Ricardo Ribalda <ribalda@xxxxxxxxxxxx>