Re: g_webcam UVC gadget causes USB\DEVICE_DESCRIPTOR_FAILURE on Windows 11

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, May 27, 2025 at 08:48:20PM -0600, Josh Cabarrus wrote:
> Bug Report: g_webcam UVC gadget incompatible with Windows 11 USB
> descriptor validation

Has this ever worked in the past?  If so, what kernel versions did work,
and can you use git bisect to track down the offending commits?

If it has never worked, any patches to change the code to make it work
would be appreciated.

> Could the maintainers investigate updating g_webcam's USB descriptors
> to meet Windows 11's stricter validation requirements? The fact that
> g_serial works but g_webcam fails suggests this is a
> descriptor-specific issue rather than hardware or driver framework
> problem.

g_serial is trivial compared to g_webcam, so this is not really a fair
comparison.  What changed in windows 11 descriptor requirements?  Do you
have a pointer to the relevant documentation for where it is explained
what has changed?

And what exact descriptors are failing here?

> I can provide:
> 
> USB protocol analyzer captures
> Testing with different Windows versions

Did windows 10 work?

> Comparison with working UVC implementations

Great, that might be the simplest, what descriptors work, and what do
not?

thanks,

greg k-h