linux-kernel - Re: [PATCH 1/3] usb: xhci: Simplify update_ring_for_set_deq

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Message-ID: <e3ca349d-c77d-4643-9865-f9991b34540f@linux.intel.com>
Date: Fri, 21 Feb 2025 15:23:11 +0200
From: Mathias Nyman <mathias.nyman@...ux.intel.com>
To: Michal Pecio <michal.pecio@...il.com>,
 Mathias Nyman <mathias.nyman@...el.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
 Niklas Neronin <niklas.neronin@...ux.intel.com>
Subject: Re: [PATCH 1/3] usb: xhci: Simplify
 update_ring_for_set_deq_completion()

On 21.2.2025 0.44, Michal Pecio wrote:
> This function checks if the queued Set Deq pointer really belongs to the
> ring it was queued on and updates the ring's dequeue state. It also used
> to count free TRBs, but that part has been removed.
> 
> The code is needlessly complex and inefficent, walking TRBs one by one.
> And it could "jump off the segment into la-la-land" if a segment doesn't
> end with a link TRB or if the link points to another link.
> 
> Make if faster, simpler and more robust. Upgrade xhci_dbg() to xhci_err()
> because this situation is a bug and shouldn't happen.
> 
> Signed-off-by: Michal Pecio <michal.pecio@...il.com>


update_ring_for_set_deq_completion() isn't needed anymore.
Niklas already wrote a patch to remove it.

It's sitting in my for-usb-next branch

https://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git/commit/?h=for-usb-next&id=ee7dab196a7dfc48a1608274329323cb10b4340d

Thanks
Mathias