linux-kernel - Re: [RFC PATCH 00/10] Tegra XHCI support

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Date:	Thu, 15 May 2014 13:44:30 -0700
From:	Andrew Bresticker <abrestic@...omium.org>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	devicetree@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>, linux-usb@...r.kernel.org,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Russell King <linux@....linux.org.uk>,
	Peter De Schrijver <pdeschrijver@...dia.com>,
	Prashant Gaikwad <pgaikwad@...dia.com>,
	Mike Turquette <mturquette@...aro.org>,
	Kishon Vijay Abraham I <kishon@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Mathias Nyman <mathias.nyman@...el.com>,
	Grant Likely <grant.likely@...aro.org>,
	Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [RFC PATCH 00/10] Tegra XHCI support

On Thu, May 15, 2014 at 12:33 PM, Stephen Warren <swarren@...dotorg.org> wrote:
> On 05/14/2014 06:32 PM, Andrew Bresticker wrote:
>> This is a first pass at the host and PHY drivers necessary for USB3.0
>> support on Tegra114 and Tegra124.  The Tegra XHCI host controller requires
>> external firmware [1] which must be loaded before using any USB ports owned
>> by the controller.  The XUSB PHY driver handles mapping and enabling of
>> the UTMI, HSIC, and SuperSpeed pads to the XHCI controller.
>>
>> Tested on a Venice2 with a variety of USB2.0 and USB3.0 memory sticks
>> and ethernet dongles.
>>
>> Notes:
>>  - I've included support for Tegra114, but since I don't have Tegra114-based
>>    hardware, it is completely untested.
>>  - The PCIe and SATA PHYs also are programmed using the XUSB_PADCTL space
>>    as well.  At least some of the code can be re-used, specifically with
>>    respect to lane programming.  I believe Thierry is working on the PCIe
>>    parts of this.
>
> If I understand the HW correctly, there's a separate "pad control" HW
> block that provides routing/sharing of signals from USB2(?), USB3, SATA,
> and PCIe to the pads.
>
> I believe Thierry is working on exposing this block as a pinctrl driver,
> or at least something that the other drivers can call into in order to
> configure that block. It'd be good if you can co-ordinate with him to
> rebase this driver on top of that, rather than (I assume; haven't read
> the code yet...) directly manipulating the padctrl registers inside each
> of the different drivers.

Yes, ideally i'd like to rebase this on top of Theirry's series once
it's ready.  It sounds like there will be a pinctrl driver which
handles the lane muxing between XUSB, PCIe, and SATA and a generic PHY
driver will deal wit the actual PHY programming.  I'm not sure what
the PCIe and SATA PHY drivers will look like, but the XUSB one
requires quite a bit of USB-specific programming of the padctl
registers, so I'm not sure we'll be able to fit all three PHY types
into a single PHY provider driver.  Either way, there's probably a
good deal of PHY code that could be broken out and shared among the
three.
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