Re: [PATCH v3 07/10] arm/tegra: Add PWFM controller device tree probing

[Thierry Reding <thierry.reding-RM9K5IK7kjKj5M59NBduVrNAH6kLmebB@public.gmane.org>]

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* Stephen Warren wrote:
> Thierry Reding wrote at Wednesday, February 22, 2012 8:17 AM:
> > Add auxdata to instantiate a device tree for the PWFM controller and
> > include a corresponding node in the device tree.
> 
> > diff --git a/arch/arm/boot/dts/tegra30.dtsi b/arch/arm/boot/dts/tegra30.dtsi
> 
> > +	pwm: pwm@7000a000 {
> > +		compatible = "nvidia,tegra20-pwm";
> > +		reg = <0x7000a000 0x100>;
> > +		#pwm-cells = <2>;
> > +	};
> 
> The compatible value probably should list both Tegra30 and Tegra20, so
> we can know exactly which HW is present, just in case we need to turn
> on some bug-fix only for one of the variants:
> 
>     compatible = "nvidia,tegra30-pwm", "nvidia,tegra20-pwm";

I'm confused. If I know exactly that the hardware is Tegra30 (which it
definitely should be if I include tegra30.dtsi), then why list "tegra20-pwm"
as compatible?

Or did you mean to list tegra30-pwm as compatible value in the PWM driver?

> Could you also write binding documentation, in particular explaining
> what the two pwm-cells are specifically for Tegra:
> 
> Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
> 
> (although perhaps that'd be part of the previous patch which implements
> the driver)

Actually for Tegra the values would be those documented in the generic
binding because Tegra uses of_pwm_simple_xlate(). Does it still make sense to
add a Tegra-specific binding?

Thierry

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