Re: [PATCH v2 1/4] ARM: dts: omap4-panda: Add USB Host support

[Florian Vaussard]

Hello,

On 06/19/2013 01:03 PM, Roger Quadros wrote:
> On 06/19/2013 01:10 PM, Benoit Cousson wrote:
> > On 06/19/2013 02:46 AM, Tony Lindgren wrote:
> > > * Roger Quadros <rogerq@xxxxxx> [130619 00:42]:
> > > > Hi Benoit,
> > > >
> > > > On 06/19/2013 04:17 AM, Benoit Cousson wrote:
> > > > > Hi Roger,
> > > > >
> > > > > On 06/18/2013 11:04 AM, Roger Quadros wrote:
> > > > > > Provide the RESET and Power regulators for the USB PHY,
> > > > > > the USB Host port mode and the PHY device.
> > > > > >
> > > > > > Also provide pin multiplexer information for the USB host
> > > > > > pins.
> > > > > >
> > > > > > Signed-off-by: Roger Quadros <rogerq@xxxxxx>
> > > > > > ---
> > > > > >     arch/arm/boot/dts/omap4-panda-common.dtsi |   62 +++++++++++++++++++++++++++++
> > > > > >     1 files changed, 62 insertions(+), 0 deletions(-)
> > > > > >
> > > > > > diff --git a/arch/arm/boot/dts/omap4-panda-common.dtsi b/arch/arm/boot/dts/omap4-panda-common.dtsi
> > > > > > index 00cbaa5..7a21e8e 100644
> > > > > > --- a/arch/arm/boot/dts/omap4-panda-common.dtsi
> > > > > > +++ b/arch/arm/boot/dts/omap4-panda-common.dtsi
> > > > > > @@ -59,6 +59,42 @@
> > > > > >                 "AFML", "Line In",
> > > > > >                 "AFMR", "Line In";
> > > > > >         };
> > > > > > +
> > > > > > +    /* HS USB Port 1 RESET */
> > > > > > +    hsusb1_reset: hsusb1_reset_reg {
> > > > > > +        compatible = "regulator-fixed";
> > > > > > +        regulator-name = "hsusb1_reset";
> > > > > > +        regulator-min-microvolt = <3300000>;
> > > > > > +        regulator-max-microvolt = <3300000>;
> > > > > > +        gpio = <&gpio2 30 0>;    /* gpio_62 */
> > > > > > +        startup-delay-us = <70000>;
> > > > > > +        enable-active-high;
> > > > > > +    };
> > > > >
> > > > > Is this really a regulator? Or just a GPIO line used to reset the USB PHY?
> > > >
> > > > It is in fact a GPIO line used as reset.
> > > > > If this is the case, I don't think it should be represented as a regulator.
> > > >
> > > > Why not? I think it fits very well in the regulator device model.
> >
> > I'm not sure fitting very well is the correct term.
> > It works, for sure, but it is no different than when we were trying to abuse the regulator fmwk to enable the 32k clock in phoenix.
> > It is just a hack.
>
> The only difference is there is a dedicated framework for clocks. Since there is nothing specific to
> handle reset lines it is left to the driver writer how he wants to manage it.

There is a proposed binding for gpio-controlled reset lines, but it is 
not yet merged [1].
I guess it can fit most usage patterns, and it can be an interesting 
move in the future.

Regards,

Florian

[1] http://thread.gmane.org/gmane.linux.drivers.devicetree/36830
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