Re: [PATCH] usb: xhci: fix maximum event ring segments calculation

[Thorsten Leemhuis]

On 8/31/26 13:28, Thorsten Leemhuis wrote:
> On 8/31/26 11:21, Mathias Nyman wrote:
>> On 8/31/26 09:55, Thorsten Leemhuis wrote:
>>> On 8/30/26 05:12, Pierre-David Belanger wrote:
>>>> The failure on 08dbfad3f504:
>>>>
>>>>    xhci_hcd 0000:00:04.0: xHCI Host Controller
>>>>    xhci_hcd 0000:00:04.0: new USB bus registered, assigned bus number 1
>>>>    xhci_hcd 0000:00:04.0: Failed to allocate interrupter erst
>>>>    xhci_hcd 0000:00:04.0: can't setup: -12
>>>>    xhci_hcd 0000:00:04.0: USB bus 1 deregistered
>>>>    xhci_hcd 0000:00:04.0: init 0000:00:04.0 fail, -12
>>>>    xhci_hcd 0000:00:04.0: probe with driver xhci_hcd failed with
>>>> error -12
>>> Sadly this missed -rc1, wonder why it wasn't submitted for it to prevent
>>> more people from running into this, but whatever, that's ship has sailed.
>>
>> Looks like at least QEMU and Mediatek users were hit by this issue.
> 
> Ahh, good to known. And thx for sending one of the fixes to Greg
> meanwhile (saw that by chance).
>> Note that this is a v7.3-rc1 regression which was found during merge
>> window for v7.3-rc1.
>> v7.3-rc1 came out a few hours ago.
>> I can't resolve it much earlier than this.
> Out of curiosity: why?
> 
> Just ignore the question if it was something like "real life got in the
> way" or "it fell through the cracks" -- that's how it is sometimes, no
> worries. But in other cases I'd be glad if you could take a few minutes
> if you have them to satisfy my curiosity, as in preparation for a
> maintainer summit proposal I sent[1] I'm just trying to understand
> better why regression fixes sometimes take quite a while from submission
> to landing in mainline

For the record (sorry, this should have bin in above mail!), as it might
sound hostile without context, as obviously there would not have been
enough time to fix this if the issue would only have become known during
the end of the merge window. But that is not the case here afaics
(please correct me if I'm wrong!), as the first patch to fix this was
afaics submitted on 2026-08-20:

https://lore.kernel.org/linux-usb/7e6648ad-7459-4248-8c6c-227cfc2586d8@xxxxxxxxxxxxxxx/

> [1]
> https://lore.kernel.org/all/75dc0e2d-2deb-4776-977c-1de7c33465e1@xxxxxxxxxxxxx/

Ciao, THorsten