Re: [PATCH v2] usb: core: add USB_QUIRK_NO_BOS for devices that hang on BOS descriptor

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Jun 04, 2026 at 04:56:19PM +0200, Michal Pecio wrote:
> On Mon, 8 Dec 2025 06:12:15 +0900, Greg KH wrote:
> > Ok, I can duplicate this here.  Maybe we just don't ask for the BOS
> > descriptor if no one needs/asks for it.  I can play with that later
> > and see if that helps as I'm sure this isn't going to be the only
> > device that can't handle the BOS descriptor if Windows isn't querying
> > for it, so we don't want to make a huge quirk table if we don't have
> > to.
> 
> Hi Greg and others,
> 
> The workaround is now in, but if somebody is interested in getting rid
> of it, it might suffice to make kernel BOS requests more Windows-like,
> since these devices work fine with Windows (and Windows queries BOS).
> 
> By monitoring Windows 10 in a VM I found two key differences: Windows
> fetches BOS *after* the configuration descriptor, and it requests 255
> bytes at once in its first attempt (there is likely a second attempt
> if BOS length exceeds 255, but I don't have such a device to test).
> 
> Any chance that the change below is enough for these video grabbers?

Have you tried it?  I'm away from my device for a few more weeks and
can't do it myself.

thanks,

greg k-h