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Date:   Tue, 14 Aug 2018 12:02:20 +0100
From:   Daniel Thompson <daniel.thompson@linaro.org>
To:     Joseph Salisbury <joseph.salisbury@canonical.com>
Cc:     ard.biesheuvel@linaro.org, mathias.nyman@linux.intel.com,
        gregkh@linuxfoundation.org,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [Regression] usb: xhci: Add XHCI_TRUST_TX_LENGTH for Renesas
 uPD720201
Message-ID: <20180814110220.brkfyjbtibuwzunx@holly.lan>
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On Fri, Aug 10, 2018 at 12:13:53PM -0400, Joseph Salisbury wrote:
> Hi Daniel,
> 
> A kernel bug report was opened against Ubuntu [0].? It was found the
> following patch introduced the regression:
> 
> da9970668948 ("usb: xhci: Add XHCI_TRUST_TX_LENGTH for Renesas uPD720201")

I can see nothing in http://pad.lv/1773704 that indicates a regression
in this patch. How could there be? The patch does not not alter the
behaviour of uPD720202 devices (pdev->device == 0x0015).

 
> The bug reporter claims there is a typo in the patch that caused the
> regression.? I built a test kernel with a change to the suspected typo
> and the bug reporter claims it resolved the regression.? My test kernel
> had the following change:
> 
> -?????????????????????? pdev->device == 0x0014)
> +?????????????????????? pdev->device == 0x0015)
> 
> I was hoping to get your feedback, since you are the patch author.? Do
> you think this is an actual typo, or maybe there really needs to be two
> quirks?

No, it is a not a typo (and the change above *does* introduce a regression
;-) ). From this git logs I believe that:

  0x0014 -> uPD720201
  0x0015 -> uPD720202


Daniel.