Re: [PATCH] xhci: Fix USB 3.1 enumeration issues by increasing roothub power-on-good delay

Greg KH
2021-11-06T14:41:56Z

On Fri, Nov 05, 2021 at 09:56:59PM +0200, Mathias Nyman wrote:
> On 5.11.2021 18.15, Greg KH wrote:
> > On Fri, Nov 05, 2021 at 06:00:36PM +0200, Mathias Nyman wrote:
> >> Some USB 3.1 enumeration issues were reported after the hub driver removed
> >> the minimum 100ms limit for the power-on-good delay.
> >>
> >> Since commit 90d28fb53d4a ("usb: core: reduce power-on-good delay time of
> >> root hub") the hub driver sets the power-on-delay based on the
> >> bPwrOn2PwrGood value in the hub descriptor.
> >>
> >> xhci driver has a 20ms bPwrOn2PwrGood value for both roothubs based
> >> on xhci spec section 5.4.8, but it's clearly not enough for the
> >> USB 3.1 devices, causing enumeration issues.
> >>
> >> Tests indicate full 100ms delay is needed.
> >>
> >> Reported-by: Walt Jr. Brake <mr.yming81@gmail.com>
> >> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
> >
> > So this needs:
> > Fixes: 90d28fb53d4a ("usb: core: reduce power-on-good delay time of root hub")
> > right?
>
> I guess so, not sure on "Fixes" policy here.
>
> This patch fixes an xhci issue revealed by ("usb: core: reduce power-on-good delay time of root hub")
> That original patch itself looks correct, but these two patches should really go together to
> avoid any enumeration issues.

Great, I'll use that tag for now so that it will get backported
properly.

greg k-h