Subject: Re: [PATCH 1/2] arm64: tegra: Add pinmux for PWM-based DFLL support on Shield platform

From: Thierry Reding <[email-masked]>
Date: Fri, 22 Mar 2019 10:52:44 +0100

On Fri, Mar 22, 2019 at 03:11:10PM +0800, Joseph Lo wrote:
> Add pinmux for PWM-based DFLL support on Shield platform.
> 
> Signed-off-by: Joseph Lo <[email-masked]>
> ---
>  arch/arm64/boot/dts/nvidia/tegra210-p2894.dtsi | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)

There's been some discussion recently about moving away from programming
pinmux in the kernel because it isn't always safe to do that. The idea
is that early boot firmware (typically cboot) will already have set up
the pinmux, so there's no need to do it again in the kernel.

These look like you're going to change this pin to/from tristate at
runtime, so perhaps that's the kind of thing that we're okay with?

Adding Stephen for visibility.

Thierry

> diff --git a/arch/arm64/boot/dts/nvidia/tegra210-p2894.dtsi b/arch/arm64/boot/dts/nvidia/tegra210-p2894.dtsi
> index 88a4b9333d84..c668f16c8574 100644
> --- a/arch/arm64/boot/dts/nvidia/tegra210-p2894.dtsi
> +++ b/arch/arm64/boot/dts/nvidia/tegra210-p2894.dtsi
> @@ -1318,6 +1318,20 @@
>  				nvidia,open-drain = <TEGRA_PIN_DISABLE>;
>  			};
>  		};
> +
> +		dvfs_pwm_active_state: dvfs_pwm_active {
> +			dvfs_pwm_pbb1 {
> +				nvidia,pins = "dvfs_pwm_pbb1";
> +				nvidia,tristate = <TEGRA_PIN_DISABLE>;
> +			};
> +		};
> +
> +		dvfs_pwm_inactive_state: dvfs_pwm_inactive {
> +			dvfs_pwm_pbb1 {
> +				nvidia,pins = "dvfs_pwm_pbb1";
> +				nvidia,tristate = <TEGRA_PIN_ENABLE>;
> +			};
> +		};
>  	};
>  
>  	serial@70006000 {
> -- 
> 2.21.0
> 
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