linux-kernel - Re: [PATCH RESEND V4 5/9] of: Add NVIDIA Tegra xHCI controller binding

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Message-ID: <20141030135500.GC19802@ulmo.nvidia.com>
Date:	Thu, 30 Oct 2014 14:55:02 +0100
From:	Thierry Reding <thierry.reding@...il.com>
To:	Andrew Bresticker <abrestic@...omium.org>
Cc:	Stephen Warren <swarren@...dotorg.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...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>,
	Russell King <linux@....linux.org.uk>,
	Jassi Brar <jassisinghbrar@...il.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Mathias Nyman <mathias.nyman@...el.com>,
	Grant Likely <grant.likely@...aro.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Arnd Bergmann <arnd@...db.de>,
	Kishon Vijay Abraham I <kishon@...com>,
	"devicetree@...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" <linux-usb@...r.kernel.org>
Subject: Re: [PATCH RESEND V4 5/9] of: Add NVIDIA Tegra xHCI controller
 binding

On Wed, Oct 29, 2014 at 09:37:14AM -0700, Andrew Bresticker wrote:
> On Wed, Oct 29, 2014 at 2:43 AM, Thierry Reding
> <thierry.reding@...il.com> wrote:
> > On Tue, Oct 28, 2014 at 03:27:50PM -0700, Andrew Bresticker wrote:
> > [...]
> >> diff --git a/Documentation/devicetree/bindings/pinctrl/nvidia,tegra124-xusb-padctl.txt b/Documentation/devicetree/bindings/pinctrl/nvidia,tegra124-xusb-padctl.txt
> > [...]
> >> +Optional properties:
> >> +-------------------
> >> +- vbus-{0,1,2}-supply: VBUS regulator for the corresponding UTMI pad.
> >> +- vddio-hsic-supply: VDDIO regulator for the HSIC pads.
> >> +- nvidia,usb3-port-{0,1}-lane: PCIe/SATA lane to which the corresponding USB3
> >> +  port is mapped.  See <dt-bindings/pinctrl/pinctrl-tegra-xusb.h> for the list
> >> +  of valid values.
> >
> > I dislike how we now need to provide a list of all pins in the header
> > file, where previously we used strings for this. This could become very
> > ugly if the set of pins changes in future generations of this IP block.
> >
> > Could we instead derive this from the pinmux nodes? For example you have
> > this in the example below:
> >
> >         usb3p0 {
> >                 nvidia,lanes = "pcie-0";
> >                 ...
> >         };
> >
> > Perhaps what we need is to either key off the node name or add another
> > property, such as:
> >
> >         nvidia,usb3-port = <0>;
> >
> > This would match the nvidia,usb2-port property that you've added below.
> 
> That is actually how I described the USB3 port to SS lane mapping
> originally, but in review of an earlier version of this series,
> Stephen suggested that I make it a separate, not pinconfig property
> since it wasn't a value written directly to the hardware.  I'm fine
> with changing it back as the pinconfig property makes more sense to me
> as well.

Hmm... I had considered it a mux option of the specific lane. If the
function is usb3, it'd still need to be muxed to one of the ports. So
it's additional information associated with the usb3 function.

I did look through the driver changes and can't really make out which
part of the code actually performs this assignment. Can you point me to
it?

Thierry

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