Re: [PATCH v5 2/3] media: uvcvideo: add UVC_QUIRK_CTRL_THROTTLE for fragile firmware

Michal Pecio
2026-04-09T08:02:54Z

On Thu, 9 Apr 2026 08:45:17 +0200, Ricardo Ribalda wrote:
> Hi JP
>
> On Tue, 31 Mar 2026 at 02:38, JP Hein <jp@jphein.com> wrote:
> >
> > Some USB webcams have firmware that crashes when it receives rapid
> > consecutive UVC control transfers (SET_CUR). The Razer Kiyo Pro
> > (1532:0e05) is one such device -- after several hundred rapid
> > control changes over a few seconds, the device stops responding
> > entirely, triggering an xHCI stop-endpoint command timeout that
> > causes the host controller to be declared dead, disconnecting every
> > USB device on the bus.
>
> A usb device shall not be able crash the whole USB host. I believe
> that you already captured some logs and the USB guys are looking into
> it. I'd really like to hear what they have to say after reviewing
> them.

Sorry, I forgot about this bug. I will take a closer look at logs
later today.

I see that there is a case which crashes the host controller, but
without dynamic debug. It would be helpful if this can be reproduced
with debug enabled.

In the future, please also make sure that there are no unrelated
devices spamming dmesg, like "slot 17 ep 2" in those "stall" logs.
Please find this device and disconnect it or unbind its driver.

The initial cause of all that may really be the device getting
locked up for no good reason, but not 100% sure yet.

Regards,
Michal