Re: Regression - commit 719de070f764 usb: xhci-pci: add support for hosts with zero USB3 ports

["Neronin, Niklas" <niklas.neronin@linux.intel.com>]

On 10/10/2025 16.12, Michal Kubecek wrote:
> On Tue, Aug 26, 2025 at 12:04:16PM GMT, Niklas Neronin wrote:
>> Add xhci support for PCI hosts that have zero USB3 ports.
>> Avoid creating a shared Host Controller Driver (HCD) when there is only
>> one root hub. Additionally, all references to 'xhci->shared_hcd' are now
>> checked before use.
>>
>> Only xhci-pci.c requires modification to accommodate this change, as the
>> xhci core already supports configurations with zero USB3 ports. This
>> capability was introduced when xHCI Platform and MediaTek added support
>> for zero USB3 ports.
>>
>> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220181
>> Tested-by: Nick Nielsen <nick.kainielsen@free.fr>
>> Tested-by: grm1 <grm1@mailbox.org>
>> Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
> 
> Hello,
> 
> while testing 6.18 merge window snapshots, I hit an issue which bisected
> to this patch, mainline commit 719de070f764 ("usb: xhci-pci: add support
> for hosts with zero USB3 ports").
> 
> When booting any kernel with it, my keyboard attached to USB port
> intended for it does not respond. Comparing the logs between "good" and
> "bad" kernel boot, it looks like hubs 9 and 10 are not detected at all
> when booting a kernel with commit 719de070f764.
> 

Hello,

Thank you for reporting.

A fix has been proposed in this thread:
https://lore.kernel.org/linux-usb/CABpa4MA9unucCoKtSdzJyOLjHNVy+Cwgz5AnAxPkKw6vuox1Nw@mail.gmail.com/

The specific fix:
https://lore.kernel.org/linux-usb/20251009142911.6069c164.michal.pecio@gmail.com/

Best Regards,
Niklas