Re: [RFC PATCH v2 1/3] usb: dwc3: msm: Add device tree binding information

From: "Ivan T. Ivanov" <iivanov@mm-sol.com>
To: Stephen Warren <swarren@wwwdotorg.org>
Cc: balbi@ti.com, rob.herring@calxeda.com, pawel.moll@arm.com,
	mark.rutland@arm.com, ian.campbell@citrix.com, rob@landley.net,
	gregkh@linuxfoundation.org, grant.likely@linaro.org,
	idos@codeaurora.org, mgautam@codeaurora.org,
	devicetree@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
	linux-omap@vger.kernel.org, linux-arm-msm@vger.kernel.org
Subject: Re: [RFC PATCH v2 1/3] usb: dwc3: msm: Add device tree binding information
Date: Wed, 14 Aug 2013 10:18:30 +0300	[thread overview]
Message-ID: <1376464710.2208.31.camel@iivanov-dev.int.mm-sol.com> (raw)
In-Reply-To: <520A8FA9.2080603@wwwdotorg.org>

Hi,

On Tue, 2013-08-13 at 13:57 -0600, Stephen Warren wrote: 
> On 08/09/2013 03:53 AM, Ivan T. Ivanov wrote:
> > From: "Ivan T. Ivanov" <iivanov@mm-sol.com>
> > 
> > MSM USB3.0 core wrapper consist of USB3.0 IP (SNPS)
> > and HS, SS PHY's controll and configuration registers.
> 
> s/controll/control/
> 

Thanks.

> > It could operate in device mode (SS, HS, FS) and host
> > mode (SS, HS, FS, LS).
> 
> > diff --git a/Documentation/devicetree/bindings/usb/msm-ssusb.txt b/Documentation/devicetree/bindings/usb/msm-ssusb.txt
> 
> > +MSM SuperSpeed DWC3 USB SoC controller
> > +
> > +Required properities :
> > +- compatible : sould be "qcom,dwc3-hsphy";
> ...
> > +Required properities :
> > +- compatible : sould be "qcom,dwc3-ssphy";
> 
> I would expect different compatible values to be documented in different
> files.

It is easy to see connection between them when they are in
one file. Drivers are useless without each other. 

> 
> > +Optional properties :
> > +- gdsc-supply : phandle to the globally distributed switch controller
> > +  regulator node to the USB controller.
> 
> Which of the 3 compatible values that were described above is that
> property optional for?

"qcom,dwc3". I will make this more explicit. 

> 
> > +Sub nodes:
> > +- Sub node for "DWC3 USB3 controller".
> > +  This sub node is required property for device node. The properties
> > +  of this subnode are specified in dwc3.txt.
> 
> Why not represent the PHY and USB controller as separate top-level
> nodes? They can point at each-other with phandles if they need to know
> each-others' identity.

"qcom,dwc3" (glue layer) driver have to be loaded before "snps,dwc3",
actual USB3 IP. "qcom,dwc3" provide required clocks and power supplies
to the USB3 IP core.

Regards,
Ivan