On Tue Oct 21 10:36:17 2025 +0000, Ricardo Ribalda wrote:
> Some devices, like the Grandstream GUV3100 webcam, have an invalid UVC
> descriptor where multiple entities share the same ID, this is invalid
> and makes it impossible to make a proper entity tree without heuristics.
>
> We have recently introduced a change in the way that we handle invalid
> entities that has caused a regression on broken devices.
>
> Implement a new heuristic to handle these devices properly.
>
> Reported-by: Angel4005 <[email protected]>
> Closes:
> https://lore.kernel.org/linux-media/CAOzBiVuS7ygUjjhCbyWg-KiNx+HFTYnqH5+GJhd6cYsNLT=d...@mail.gmail.com/
> Fixes: 0e2ee70291e6 ("media: uvcvideo: Mark invalid entities with id
> UVC_INVALID_ENTITY_ID")
> Cc: [email protected]
> Signed-off-by: Ricardo Ribalda <[email protected]>
> Reviewed-by: Hans de Goede <[email protected]>
> Signed-off-by: Hans Verkuil <[email protected]>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/usb/uvc/uvc_driver.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
---
diff --git a/drivers/media/usb/uvc/uvc_driver.c
b/drivers/media/usb/uvc/uvc_driver.c
index fb6afb8e84f0..ee4f54d68349 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -167,13 +167,26 @@ static struct uvc_entity *uvc_entity_by_reference(struct
uvc_device *dev,
static struct uvc_streaming *uvc_stream_by_id(struct uvc_device *dev, int id)
{
- struct uvc_streaming *stream;
+ struct uvc_streaming *stream, *last_stream;
+ unsigned int count = 0;
list_for_each_entry(stream, &dev->streams, list) {
+ count += 1;
+ last_stream = stream;
if (stream->header.bTerminalLink == id)
return stream;
}
+ /*
+ * If the streaming entity is referenced by an invalid ID, notify the
+ * user and use heuristics to guess the correct entity.
+ */
+ if (count == 1 && id == UVC_INVALID_ENTITY_ID) {
+ dev_warn(&dev->intf->dev,
+ "UVC non compliance: Invalid USB header. The streaming
entity has an invalid ID, guessing the correct one.");
+ return last_stream;
+ }
+
return NULL;
}
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