linux-kernel - Re: [PATCH] ARM: dts: imx6: skov: add pwm-regulator to control the panel's VCOM

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Message-ID: <20220611093103.GI254723@dragon>
Date:   Sat, 11 Jun 2022 17:31:03 +0800
From:   Shawn Guo <shawnguo@...nel.org>
To:     Ulrich Ölmann <u.oelmann@...gutronix.de>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        NXP Linux Team <linux-imx@....com>,
        Fabio Estevam <festevam@...il.com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Oleksij Rempel <o.rempel@...gutronix.de>,
        Juergen Borleis <jbe@...gutronix.de>,
        Michael Grzeschik <m.grzeschik@...gutronix.de>,
        Marco Felsch <m.felsch@...gutronix.de>,
        Lucas Stach <l.stach@...gutronix.de>,
        Søren Andersen <san@...v.dk>,
        Sam Ravnborg <sam@...nborg.org>
Subject: Re: [PATCH] ARM: dts: imx6: skov: add pwm-regulator to control the
 panel's VCOM

On Tue, May 17, 2022 at 09:18:14AM +0200, Ulrich Ölmann wrote:
> Skov's i.MX6 based boards come in different flavors which have different panels
> attached. For optimal contrast experience each panel type needs an individual
> common voltage (VCOM) to drive its TFT backplane. The latter is generated by an
> LCD bias supply IC controlled by a pwm as input signal. Introduce a pwm-
> regulator to describe this hardware property and parameterize it appropriately
> for the different boards.
> 
> Signed-off-by: Ulrich Ölmann <u.oelmann@...gutronix.de>
> ---
>  arch/arm/boot/dts/imx6q-skov-reve-mi1010ait-1cp1.dts |  6 ++++++
>  arch/arm/boot/dts/imx6qdl-skov-cpu.dtsi              | 10 ++++++++++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/imx6q-skov-reve-mi1010ait-1cp1.dts b/arch/arm/boot/dts/imx6q-skov-reve-mi1010ait-1cp1.dts
> index 7f1f19b74bfa..a3f247c722b4 100644
> --- a/arch/arm/boot/dts/imx6q-skov-reve-mi1010ait-1cp1.dts
> +++ b/arch/arm/boot/dts/imx6q-skov-reve-mi1010ait-1cp1.dts
> @@ -125,3 +125,9 @@ MX6QDL_PAD_EIM_D23__GPIO3_IO23		0x1b0b0
>  		>;
>  	};
>  };
> +
> +&reg_tft_vcom {
> +	regulator-min-microvolt = <3160000>;
> +	regulator-max-microvolt = <3160000>;
> +	voltage-table = <3160000 73>;
> +};
> diff --git a/arch/arm/boot/dts/imx6qdl-skov-cpu.dtsi b/arch/arm/boot/dts/imx6qdl-skov-cpu.dtsi
> index 77a91a97e6cf..3def1b621c8e 100644
> --- a/arch/arm/boot/dts/imx6qdl-skov-cpu.dtsi
> +++ b/arch/arm/boot/dts/imx6qdl-skov-cpu.dtsi
> @@ -149,6 +149,16 @@ reg_can2_stby: regulator-can2-stby {
>  		gpio = <&gpio4 11 GPIO_ACTIVE_LOW>;
>  	};
>  
> +	reg_tft_vcom: regulator-tft-vcom {
> +		compatible = "pwm-regulator";
> +		pwms = <&pwm3 0 20000 0>;
> +		regulator-name = "tft_vcom";
> +		regulator-min-microvolt = <3600000>;
> +		regulator-max-microvolt = <3600000>;
> +		regulator-always-on;

You want it to be unmanaged and always-on?

Shawn

> +		voltage-table = <3600000 26>;
> +	};
> +
>  	reg_vcc_mmc: regulator-vcc-mmc {
>  		compatible = "regulator-fixed";
>  		pinctrl-names = "default";
> -- 
> 2.30.2
>