linux-kernel - Re: [PATCH V3 3/4] pwm: tegra: Add DT binding details to configure pin in suspends/resume

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Date:   Thu, 6 Apr 2017 16:26:16 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Laxman Dewangan <ldewangan@...dia.com>, <thierry.reding@...il.com>,
        <robh+dt@...nel.org>
CC:     <mark.rutland@....com>, <linux-pwm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V3 3/4] pwm: tegra: Add DT binding details to configure
 pin in suspends/resume


On 06/04/17 15:21, Laxman Dewangan wrote:
> In some of NVIDIA Tegra's platform, PWM controller is used to
> control the PWM controlled regulators. PWM signal is connected to
> the VID pin of the regulator where duty cycle of PWM signal decide
> the voltage level of the regulator output.
> 
> The tristate (high impedance of PWM pin form Tegra) also define

s/form/from/
s/define/defines/

> one of the state of PWM regulator which needs to be configure in
> suspend state of system.

It maybe clearer to say that when the system enters suspend the
regulator requires the pwm output to be tristated.

> Add DT binding details to provide the pin configuration state
> from PWM and pinctrl DT node in suspend and active state of
> the system.
> 
> Signed-off-by: Laxman Dewangan <ldewangan@...dia.com>
> ---
> Changes from v1:
> - Use standard pinctrl names for sleep and active state.
> 
>  .../devicetree/bindings/pwm/nvidia,tegra20-pwm.txt | 43 ++++++++++++++++++++++
>  1 file changed, 43 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
> index b4e7377..4128cdc 100644
> --- a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
> +++ b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
> @@ -19,6 +19,19 @@ Required properties:
>  - reset-names: Must include the following entries:
>    - pwm
>  
> +Optional properties:
> +============================
> +In some of the interface like PWM based regulator device, it is required
> +to configure the pins differently in different states, especially in suspend
> +state of the system. The configuration of pin is provided via the pinctrl
> +DT node as detailed in the pinctrl DT binding document
> +	Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
> +
> +The PWM node will have following optional properties.
> +pinctrl-names:	Pin state names. Must be "default" and "sleep".
> +pinctrl-0:	Node handle for the default/active state of pi configurations.

s/pi/pin/
s/Node handle/phandle/

> +pinctrl-1:	Node handle for the sleep state of pin configurations.
> +
>  Example:
>  
>  	pwm: pwm@...0a000 {
> @@ -29,3 +42,33 @@ Example:
>  		resets = <&tegra_car 17>;
>  		reset-names = "pwm";
>  	};
> +
> +
> +Example with the pin configuration for suspend and resume:
> +=========================================================
> +Pin PE7 is used as PWM interface.

Nit-pick. On what devices? Sounds like this is verbatim. Maybe state
what device this is an example for.

Jon

-- 
nvpublic