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

- From: Greg KH \<gregkh@linuxfoundation.org\>
- Date: 2021-11-05 16:16:00 
- List: linux-usb
- Page: https://ratatoskr.run/linux-usb/2021/11/1564015
- Thread: https://ratatoskr.run/linux-usb/2021/11/1559781/t.md

```text
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 <redacted>
> Signed-off-by: Mathias Nyman <redacted>

So this needs:
	Fixes: 90d28fb53d4a ("usb: core: reduce power-on-good delay time of root hub")
right?

thanks,

greg k-h
```