linux-kernel - Re: [PATCH 0/3] xhci: Some improvement for Etron xHCI host

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Message-ID: <CAHN5xi1hwMi3v9j5OPJjWqtPwVHw_6AycyYeGBmApD+4RwtSZQ@mail.gmail.com>
Date: Mon, 16 Sep 2024 10:04:30 +0800
From: Kuangyi Chiang <ki.chiang65@...il.com>
To: Michał Pecio <michal.pecio@...il.com>
Cc: gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org, 
	linux-usb@...r.kernel.org, mathias.nyman@...el.com
Subject: Re: [PATCH 0/3] xhci: Some improvement for Etron xHCI host

Hi,

Thank you for testing the patch.

Michał Pecio <michal.pecio@...il.com> 於 2024年9月12日 週四 下午3:12寫道：
>
> Hi,
>
> > > I'm aware of one more bug which affects my Etron: if an error occurs
> > > on an isochronous TD, two events are generated: first the error,
> > > then "success", even if the error is on the final TRB (the common
> > > case). Then the "success" causes "TRB DMA not part of current TD"
> > > warning. I suspect that all Etron chips are the same. This should
> > > be easily reproducible by unpligging an audio/video device while
> > > streaming.
> >
> > Hmm, I don't encounter this problem.
>
> OK, I know what happened. This bug only affects SuperSpeed isochronous
> endpoints. If you don't have this kind of device, you will not see it.
> I checked that High-speed isochronous errors are reported correctly.
>
> My motivation to develop a workaround for this bug has just decreased
> another notch.
>
>
> On the other hand, I was unable to reproduce the control transfer bug.
> The exact chip I have is labeled "EtronTech EJ168A", for the record.
>
> You are right, not all transfers have the data stage and transactions
> get out of sync with segment boundaries. I modified the patch to only
> print a warning instead of queuing a No-Op and then did various things
> which use control transactions: setting baud rate on serial, changing
> the volume on audio, starting video recording on a webcam, running
> ethtool on a NIC.
>
> The warning was printed a few times, but nothing interesting happened.
> Dynamic debug was enabled on handle_tx_event() - no errors reported.
>
> Maybe a different silicon/firmware revision, or maybe it's another
> SuperSpeed-only bug, or other special conditions for it to happen?

Do you see any "Transfer error for slot..." error message?
What is the speed of your device? high speed?
I try to downgrade my ethernet adapter to high speed and do some tests,
no errors are reported in dmesg if dynamic debug is enabled.
I think it is a super speed issue, however, it doesn't happen on the high
speed device, I am not sure. So the patch will not check the speed of the
device.

>
> > Ok, I will use one quirk XHCI_ETRON_HOST for these workarounds in the
> > next patch revision.
> That was just a suggestion, you should ask Mathias Nyman, I suppose.

OK, thanks.

>
> But, again, my impression of this hardware is that it's pretty bad
> and full of bugs, and they are bizarre enough to likely be unique.
>
> Regards,
> Michal

Thanks,
Kuangyi Chiang