linux-kernel - Re: [PATCH v3 1/2] usb: host: ehci-tegra: Grab the correct UTMI pads reset

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Date:	Thu, 5 May 2016 19:05:05 +0300
From:	Tuomas Tynkkynen <tuomas.tynkkynen@....fi>
To:	Thierry Reding <thierry.reding@...il.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Stephen Warren <swarren@...dotorg.org>,
	Alexandre Courbot <gnurou@...il.com>,
	Jon Hunter <jonathanh@...dia.com>, linux-usb@...r.kernel.org,
	linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
	Tuomas Tynkkynen <tuomas.tynkkynen@....fi>
Subject: Re: [PATCH v3 1/2] usb: host: ehci-tegra: Grab the correct UTMI pads
 reset

On 05/04/2016 06:26 PM, Thierry Reding wrote:
> On Wed, May 04, 2016 at 07:57:10AM -0700, Greg Kroah-Hartman wrote:
>> On Wed, May 04, 2016 at 04:39:59PM +0200, Thierry Reding wrote:
>>> From: Thierry Reding <treding@...dia.com>
>>>
>>> There are three EHCI controllers on Tegra SoCs, each with its own reset
>>> line. However, the first controller contains a set of UTMI configuration
>>> registers that are shared with its siblings. These registers will only
>>> be reset as part of the first controller's reset. For proper operation
>>> it must be ensured that the UTMI configuration registers are reset
>>> before any of the EHCI controllers are enabled, irrespective of the
>>> probe order.
>>>
>>> Commit a47cc24cd1e5 ("USB: EHCI: tegra: Fix probe order issue leading to
>>> broken USB") introduced code that ensures the first controller is always
>>> reset before setting up any of the controllers, and is never again reset
>>> afterwards.
>>>
>>> This code, however, grabs the wrong reset. Each EHCI controller has two
>>> reset controls attached: 1) the USB controller reset and 2) the UTMI
>>> pads reset (really the first controller's reset). In order to reset the
>>> UTMI pads registers the code must grab the second reset, but instead it
>>> grabbing the first.
>>>
>>> Signed-off-by: Thierry Reding <treding@...dia.com>
...snip ...
>
> While at it, adding Tuomas who wrote the original probe order fix.
> Tuomas, does this patch look correct to you? Here's the patch in full if
> you don't have it in your inbox:
>
> 	http://patchwork.ozlabs.org/patch/618488/
>

D'oh! Yes, that patch looks correct.

- Tuomas