Re: [REGRESSION] 6.12.36+: usb: hub: post-resume delayed work triggers > uncorrected MCE / data fabric sync flood on Threadripper 7970X > (bisected to aec11e5f9c45)

[Lovekesh Solanki]

On Wed, Aug 26, 2026 at 04:40:14PM +0300, Mathias Nyman wrote:
> Roothub needs some time to settle as well, but 200ms might be excessive.
> 
> xHC can triggers wake (PME) when a connected USB3 device starts signalling wake,
> but port registers changes are not always visible to driver before link training
> between roothub and device is successful.
> 
> My educated guess is that 120ms should always be enough for the roothub.
> This is also the lecagy msleep() still apparently left in xhci resume
> to detect port changes in xhci runtime resume if there are USB3 devices.
> That msleep was supposed to be removed now that we got the hub changes.
> 
> This 120ms can probably be further tuned for roothub in some cases,
> especially if resume is due to userspace action instead of xHC wake signal (PME).
So the patch I sent above unintentionally brought the total hold from hub
and xhci side down to 120ms, which worked.

And the correct fix would be to bring USB_SS_PORT_U0_WAKE_TIME down to
120ms and clean up the msleep from xhci_resume?

I can prepare a patch that addresses both if you'd like.

Regards,
Lovekesh