Re: [PATCH 1/3] arm: dts: sun8i: V3s: Add pinctrl for pwm

[Andre Przywara <andre.przywara@arm.com>]

On Tue, 20 Jun 2023 15:00:20 -0500
Chris Morgan <macroalpha82@gmail.com> wrote:

Hi Chris,

thanks for taking care of upstreaming, cute little device.

> From: Chris Morgan <macromorgan@hotmail.com>
> 
> Add a default pinctrl for the pwm function.
> 
> Signed-off-by: Chris Morgan <macromorgan@hotmail.com>


> ---
>  arch/arm/boot/dts/sun8i-v3s.dtsi | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/sun8i-v3s.dtsi b/arch/arm/boot/dts/sun8i-v3s.dtsi
> index b001251644f7..e5977524abe2 100644
> --- a/arch/arm/boot/dts/sun8i-v3s.dtsi
> +++ b/arch/arm/boot/dts/sun8i-v3s.dtsi
> @@ -414,6 +414,11 @@ mmc1_pins: mmc1-pins {
>  				bias-pull-up;
>  			};
>  
> +			pwm_pins: pwm-pins {
> +				pins = "PB4";
> +				function = "pwm0";
> +			};
> +
>  			spi0_pins: spi0-pins {
>  				pins = "PC0", "PC1", "PC2", "PC3";
>  				function = "spi0";
> @@ -441,6 +446,8 @@ pwm: pwm@1c21400 {
>  				     "allwinner,sun7i-a20-pwm";
>  			reg = <0x01c21400 0xc>;
>  			clocks = <&osc24M>;
> +			pinctrl-0 = <&pwm_pins>;
> +			pinctrl-names = "default";

How is this supposed to work with multiple channels? There is PWM1 on
PB5. If one wants to potentially use that, we would need to add a
reference to those pins here as well, and they would all be muxed to
PWM upon the PWM controller probing?

So while I see that it's the only output pin for PWM0, this might still
need to go into the board .dts, alongside the status = "okay"; line. So
each board would specify exactly the pins it needs (PWM0 only, PWM1
only, both or none).

Otherwise I compared this against the manual and Linux pinctrl driver,
it all matches up.

Cheers,
Andre

>  			#pwm-cells = <3>;
>  			status = "disabled";
>  		};