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

Jon Hunter
2017-04-07T10:26:19Z

On 07/04/17 10:34, 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.
>
> When system enters suspend, some PWM client/slave regulator devices
> require 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@nvidia.com>
>
> ---
> Changes from v1:
> - Use standard pinctrl names for sleep and active state.
>
> Changes from V2:
> - Fix the commit message and details
> ---
> .../devicetree/bindings/pwm/nvidia,tegra20-pwm.txt | 45 ++++++++++++++++++++++
> 1 file changed, 45 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
> index b4e7377..c57e11b 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: phandle for the default/active state of pin configurations.
> +pinctrl-1: phandle for the sleep state of pin configurations.
> +
> Example:
>
> pwm: pwm@7000a000 {
> @@ -29,3 +42,35 @@ Example:
> resets = <&tegra_car 17>;
> reset-names = "pwm";
> };
> +
> +
> +Example with the pin configuration for suspend and resume:
> +=========================================================
> +Suppose pin PE7 (On Tegra210) interfaced with the regulator device and
> +it requires PWM output to be tristated when system enters suspend.
> +Following will be DT binding to achieve this:
> +
> +#include <dt-bindings/pinctrl/pinctrl-tegra.h>
> +
> + pinmux@700008d4 {
> + pwm_active_state: pwm_active_state {
> + pe7 {
> + nvidia,pins = "pe7";
> + nvidia,tristate = <TEGRA_PIN_DISABLE>;
> + };
> + };
> +
> + pwm_sleep_state: pwm_sleep_state {
> + pe7 {
> + nvidia,pins = "pe7";
> + nvidia,tristate = <TEGRA_PIN_ENABLE>;
> + };
> + };
> + };
> +
> + pwm@7000a000 {
> + /* Mandatory PWM properties */

Maybe these are mandatory for the platform, but given these are
optional, its a bit confusing.

> + pinctrl-names = "default", "sleep";
> + pinctrl-0 = <&pwm_active_state>;
> + pinctrl-1 = <&pwm_sleep_state>;
> + };

However, fine with me so ...

Acked-by: Jon Hunter <jonathanh@nvidia.com>

Cheers
Jon

--
nvpublic