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

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Date:   Tue, 17 May 2022 09:18:14 +0200
From:   Ulrich Ölmann <u.oelmann@...gutronix.de>
To:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>
Cc:     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>,
        Ulrich Ölmann <u.oelmann@...gutronix.de>
Subject: [PATCH] ARM: dts: imx6: skov: add pwm-regulator to control the panel's VCOM

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