linux-kernel - Re: [PATCH] usb: host: xhci: Fix Compliance Mode on SN65LVPE502CP Hardware

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Date:	Wed, 1 Aug 2012 14:18:40 -0700
From:	Sarah Sharp <sarah.a.sharp@...ux.intel.com>
To:	Peter Stuge <peter@...ge.se>,
	"Alexis R. Cortes" <alexis.cortes@...com>
Cc:	gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, brian.quach@...com,
	jorge.llamas@...com
Subject: Re: [PATCH] usb: host: xhci: Fix Compliance Mode on SN65LVPE502CP
 Hardware

On Wed, Aug 01, 2012 at 10:01:31PM +0200, Peter Stuge wrote:
> Hi Alexis,
> 
> Did you run the patch through checkpatch.pl before submitting it?
> 
> I think you will get a bunch of important and completely automatic
> feedback when you do that. Please fix everything that the script
> mentions.
> 
> 
> Alexis R. Cortes wrote:
> > This patch is intended to work around a known issue on the
> > SN65LVPE502CP USB3.0 re-driver that can delay the negotiation
> > between a device and the host past the usual handshake timeout,
> > and if that happens on the first insertion, the host controller
> > port will enter in Compliance Mode as per xHCI Spec. The patch
> > creates a timer which polls every 2 seconds the link state of each
> > host controller's port (this by reading the PORTSC register) and
> > recovers the port by issuing a Warm reset every time Compliance mode
> > is detected.
> 
> This is a pretty awful workaround for a teeny tiny hardware error.
> You're making systems wake up every two seconds. I don't want that on
> my system. I think making the timer settable would be nice.

Yep, it's not fun, but the timer should only run on particular HP
systems.  The alternative is "dead" ports.  Alex, can you update your
description to include that fact?

Greg and I already argued about making the timer settable via a module
parameter, and I think the basic answer was that he doesn't want a new
modparam for this.

> Also, the patch does more things than what you describe. It adds a
> new quirk, and it adds checks to set said quirk for various different
> laptop models. Each of those changes (add timer+quirk, and add checks
> to set quirk for laptops) should rather be a separate commit.

I would really rather the quirk addition and application to some machine
be in the same patch.  That's how the other quirk patches have been
applied in the past.

Sarah Sharp
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