linux-kernel - Re: [PATCH] usb: xhci: Don't unchain link TRBs on quirky HCs

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Message-ID: <ce9f5ad9-bbcc-4dd0-a7bc-8398bb7cdb67@linux.intel.com>
Date: Fri, 14 Nov 2025 14:15:24 +0200
From: Mathias Nyman <mathias.nyman@...ux.intel.com>
To: Michal Pecio <michal.pecio@...il.com>
Cc: Mathias Nyman <mathias.nyman@...el.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, linux-usb@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: xhci: Don't unchain link TRBs on quirky HCs

On 11/14/25 13:32, Michal Pecio wrote:
> On Tue, 11 Nov 2025 18:19:38 +0200, Mathias Nyman wrote:
>> On 11/7/25 12:08, Michal Pecio wrote:
>>> +static void td_to_noop(struct xhci_hcd *xhci, struct xhci_virt_ep *ep,
>>> +			struct xhci_td *td, bool flip_cycle)
>>
>> we could avoid passing xhci pointer to td_to_noop() and just grab it from
>> the xhci_virt_ep structure instead. i.e. ep->xhci
> 
> I can do a v2 if you want.
> 
> But OTOH, I didn't expect such pointer to exist (though I'm sure I must
> have seen it many times) because it doesn't seem strictly necessary.
> 
> Maybe do the reverse and get rid of ep->xhci, or stop adding new users
> and clean up existing ones along the way?
> 
> Main users are invalidate_cancelled_tds()/giveback_invalidated_tds(),
> their callers all have xhci and could easily supply it to them. And we
> even discussed removing the latter completely, but I got sidetracked by
> issues with URB_ZERO_PACKET.

Ok, I'll take this v1 now as it is.
It prevents a potential issue, and it's tested by you.

We can then later figure out how we want to clean up and refactor things.

Thanks
Mathias