[Regression] usb: xhci: Add XHCI_TRUST_TX_LENGTH for Renesas uPD720201

[Regression] usb: xhci: Add XHCI_TRUST_TX_LENGTH for Renesas uPD720201

[Joseph Salisbury]

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")

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?

Thanks,

Joe


[0] http://pad.lv/1773704

Re: [Regression] usb: xhci: Add XHCI_TRUST_TX_LENGTH for Renesas uPD720201

[Daniel Thompson]

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.