Re: [PATCH] media: uvcvideo: Add UVC_QUIRK_CTL_MSG_DELAY_1M for HIK camera

[Michal Pecio <michal.pecio@gmail.com>]

Hi Hans,

Kuangyi Chiang has also reported this to linux-usb and linked here.

On Thu, 29 Oct 2026 13:46:04 +0100, Hans de Goede wrote:
> Is this a USB-2.0 camera connected to a XHCI controller ?
> 
> And if yes, how old is this camera model ?
> 
> The reason why I'm asking this is because the EHCI USB-2.0 controller
> interface causes a natural delay between consecutive ctrl commands
> queued one by one till the start of the next USB frrame, so they get
> spaced 1 ms apart.
> 
> Where as the modern XHCI controller interface will put these
> back-to-back on the USB bus. We've seen some issues with (older) USB
> devices before where they needed some delay because they were
> originally only validated with EHCI controllers and the hw/ff assumes
> it will get some "breathing space" between control messages.

Are you sure that this wasn't possible with EHCI at all?

What sort of devices were affected? A bit surprising to see that there
is apparently no quirk for a known issue.

Regards,
Michal