[PATCH 0/4] ARM: dts: omap: omap4-epson-embt2ws: misc gpio definitions

[PATCH 0/4] ARM: dts: omap: omap4-epson-embt2ws: misc gpio definitions

[Andreas Kemnade]

Bring the system into a more defined state and do not rely
on things being initialized by bootloader.

Andreas Kemnade (4):
  ARM: dts: omap: omap4-epson-embt2ws: define GPIO regulators
  ARM: dts: omap: omap4-epson-embt2ws: wire up regulators
  ARM: dts: omap: omap4-epson-embt2ws: add unknown gpio outputs
  ARM: dts: omap: omap4-epson-embt2ws: add GPIO expander

 .../boot/dts/ti/omap/omap4-epson-embt2ws.dts  | 175 +++++++++++++++++-
 1 file changed, 171 insertions(+), 4 deletions(-)

-- 
2.39.5

[PATCH 1/4] ARM: dts: omap: omap4-epson-embt2ws: define GPIO regulators

[Andreas Kemnade]

To properly have things running after cold boot, define
GPIO regulators. Naming is based on board file.

In the vendor kernel they are enabled in a function
called bt2ws_dcdc_init() if the system is not booted just
to charge the battery.

Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
---
 .../boot/dts/ti/omap/omap4-epson-embt2ws.dts  | 73 +++++++++++++++++++
 1 file changed, 73 insertions(+)

diff --git a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
index 339e52ba3614..d6b0abba19f6 100644
--- a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
+++ b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
@@ -29,6 +29,42 @@ backlight-right {
 		power-supply = <&unknown_supply>;
 	};
 
+	cb_v18: cb-v18 {
+		pinctrl-names = "default";
+		pinctrl-0 = <&cb_v18_pins>;
+		compatible = "regulator-fixed";
+		regulator-name = "cb_v18";
+		regulator-min-microvolt = <1800000>;
+		regulator-max-microvolt = <1800000>;
+		regulator-always-on;
+		gpio = <&gpio1 28 GPIO_ACTIVE_HIGH>;
+		enable-active-high;
+	};
+
+	cb_v33: cb-v33 {
+		pinctrl-names = "default";
+		pinctrl-0 = <&cb_v33_pins>;
+		compatible = "regulator-fixed";
+		regulator-name = "cb_v33";
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+		regulator-always-on;
+		gpio = <&gpio6 30 GPIO_ACTIVE_HIGH>;
+		enable-active-high;
+	};
+
+	cb-v50 {
+		pinctrl-names = "default";
+		pinctrl-0 = <&cb_v50_pins>;
+		compatible = "regulator-fixed";
+		regulator-name = "cb_v50";
+		regulator-min-microvolt = <5000000>;
+		regulator-max-microvolt = <5000000>;
+		regulator-always-on;
+		gpio = <&gpio6 31 GPIO_ACTIVE_HIGH>;
+		enable-active-high;
+	};
+
 	chosen {
 		stdout-path = &uart3;
 	};
@@ -46,6 +82,19 @@ key-lock {
 		};
 	};
 
+	lb_v50: lb-v50 {
+		/* required for many things at the head (probably indirectly) */
+		pinctrl-names = "default";
+		pinctrl-0 = <&lb_v50_pins>;
+		compatible = "regulator-fixed";
+		regulator-name = "lb_v50";
+		regulator-min-microvolt = <5000000>;
+		regulator-max-microvolt = <5000000>;
+		regulator-always-on;
+		gpio = <&gpio1 27 GPIO_ACTIVE_HIGH>;
+		enable-active-high;
+	};
+
 	unknown_supply: unknown-supply {
 		compatible = "regulator-fixed";
 		regulator-name = "unknown";
@@ -336,6 +385,24 @@ OMAP4_IOPAD(0x1ca, PIN_OUTPUT | MUX_MODE3) /* gpio25 */
 		>;
 	};
 
+	cb_v18_pins: pinmux-cb-v18-pins {
+		pinctrl-single,pins = <
+			OMAP4_IOPAD(0x1d0, PIN_OUTPUT | MUX_MODE3) /* gpio28 */
+		>;
+	};
+
+	cb_v33_pins: pinmux-cb-v33-pins {
+		pinctrl-single,pins = <
+			OMAP4_IOPAD(0x1d2, PIN_OUTPUT | MUX_MODE3) /* gpio190 */
+		>;
+	};
+
+	cb_v50_pins: pinmux-cb-v50-pins {
+		pinctrl-single,pins = <
+			OMAP4_IOPAD(0x1d4, PIN_OUTPUT | MUX_MODE3) /* gpio191 */
+		>;
+	};
+
 	gpio_keys_pins: pinmux-gpio-key-pins {
 		pinctrl-single,pins = <
 			OMAP4_IOPAD(0x56, PIN_INPUT_PULLUP | MUX_MODE3) /* gpio35 */
@@ -387,6 +454,12 @@ OMAP4_IOPAD(0x005c, PIN_OUTPUT | MUX_MODE1)
 		>;
 	};
 
+	lb_v50_pins: pinmux-lb-v50-pins {
+		pinctrl-single,pins = <
+			OMAP4_IOPAD(0x1ce, PIN_OUTPUT | MUX_MODE3) /* gpio27 */
+		>;
+	};
+
 	mcbsp2_pins: pinmux-mcbsp2-pins {
 		pinctrl-single,pins = <
 			OMAP4_IOPAD(0x0f6, PIN_INPUT | MUX_MODE0)       /* abe_mcbsp2_clkx */
-- 
2.39.5

[PATCH 2/4] ARM: dts: omap: omap4-epson-embt2ws: wire up regulators

[Andreas Kemnade]

Wire up the regulators where usage is plausible. Do not
wire them if purpose/usage is unclear like 5V for
many things requiring lower voltages.

Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
---
 arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
index d6b0abba19f6..cc1b6080bf95 100644
--- a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
+++ b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
@@ -20,13 +20,13 @@ memory@80000000 {
 	backlight-left {
 		compatible = "pwm-backlight";
 		pwms = <&twl_pwm 1 7812500>;
-		power-supply = <&unknown_supply>;
+		power-supply = <&lb_v50>;
 	};
 
 	backlight-right {
 		compatible = "pwm-backlight";
 		pwms = <&twl_pwm 0 7812500>;
-		power-supply = <&unknown_supply>;
+		power-supply = <&lb_v50>;
 	};
 
 	cb_v18: cb-v18 {
@@ -95,11 +95,6 @@ lb_v50: lb-v50 {
 		enable-active-high;
 	};
 
-	unknown_supply: unknown-supply {
-		compatible = "regulator-fixed";
-		regulator-name = "unknown";
-	};
-
 	wl12xx_pwrseq: wl12xx-pwrseq {
 		compatible = "mmc-pwrseq-simple";
 		clocks = <&twl 1>;
@@ -308,6 +303,8 @@ mpu9150: imu@68 {
 		pinctrl-0 = <&mpu9150_pins>;
 		interrupt-parent = <&gpio2>;
 		interrupt = <7 IRQ_TYPE_LEVEL_HIGH>;
+		vddio-supply = <&cb_v18>;
+		vdd-supply = <&cb_v33>;
 		invensense,level-shifter;
 	};
 };
-- 
2.39.5

[PATCH 3/4] ARM: dts: omap: omap4-epson-embt2ws: add unknown gpio outputs

[Andreas Kemnade]

Set them to the state seen in a running system, initialized
by vendor u-boot or kernel. Add line names where they are defined in the
vendor kernel.
gpio15 resets something in the display, otherwise meaning of the
gpios is not known.

Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
---
 .../boot/dts/ti/omap/omap4-epson-embt2ws.dts  | 84 +++++++++++++++++++
 1 file changed, 84 insertions(+)

diff --git a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
index cc1b6080bf95..c8205ae89840 100644
--- a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
+++ b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
@@ -115,6 +115,65 @@ wl12xx_vmmc: wl12xx-vmmc {
 	};
 };
 
+&gpio1 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&gpio1_hog_pins &gpio1wk_hog_pins>;
+
+	lb-reset-hog {
+		gpio-hog;
+		gpios = <9 GPIO_ACTIVE_HIGH>;
+		output-low;
+		line-name = "lb_reset";
+	};
+
+	power-en-hog {
+		gpio-hog;
+		gpios = <10 GPIO_ACTIVE_HIGH>;
+		output-high;
+		line-name = "power_en";
+	};
+
+	panel-power-en-hog {
+		gpio-hog;
+		gpios = <14 GPIO_ACTIVE_HIGH>;
+		output-low;
+		line-name = "panel_power_en";
+	};
+
+	blc-r-hog {
+		gpio-hog;
+		gpios = <17 GPIO_ACTIVE_HIGH>;
+		output-low;
+		line-name = "blc_r";
+	};
+
+	blc-l-hog {
+		gpio-hog;
+		gpios = <16 GPIO_ACTIVE_HIGH>;
+		output-low;
+		line-name = "blc_l";
+	};
+
+	high-hog {
+		gpio-hog;
+		gpios = <15 GPIO_ACTIVE_HIGH /* maybe dsi to dpi chip reset? */
+			 21 GPIO_ACTIVE_HIGH
+			 26 GPIO_ACTIVE_HIGH>;
+		output-high;
+		line-name = "unknown-high";
+	};
+
+	low-hog {
+		gpio-hog;
+		gpios = <18 GPIO_ACTIVE_HIGH
+			 19 GPIO_ACTIVE_HIGH
+			 20 GPIO_ACTIVE_HIGH
+			 22 GPIO_ACTIVE_HIGH>;
+		output-low;
+		line-name = "unknown-low";
+	};
+};
+
 &i2c1 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&i2c1_pins>;
@@ -406,6 +465,22 @@ OMAP4_IOPAD(0x56, PIN_INPUT_PULLUP | MUX_MODE3) /* gpio35 */
 		>;
 	};
 
+	gpio1_hog_pins: pinmux-gpio1-hog-pins {
+		pinctrl-single,pins = <
+			OMAP4_IOPAD(0x1b4, PIN_OUTPUT | MUX_MODE3) /* gpio14 */
+			OMAP4_IOPAD(0x1b8, PIN_OUTPUT | MUX_MODE3) /* gpio16 */
+			OMAP4_IOPAD(0x1ba, PIN_OUTPUT | MUX_MODE3) /* gpio17 */
+
+			OMAP4_IOPAD(0x1b6, PIN_OUTPUT | MUX_MODE3) /* gpio15 */
+			OMAP4_IOPAD(0x1bc, PIN_OUTPUT | MUX_MODE3) /* gpio18 */
+			OMAP4_IOPAD(0x1be, PIN_OUTPUT | MUX_MODE3) /* gpio19 */
+			OMAP4_IOPAD(0x1c0, PIN_OUTPUT | MUX_MODE3) /* gpio20 */
+			OMAP4_IOPAD(0x1c2, PIN_OUTPUT | MUX_MODE3) /* gpio21 */
+			OMAP4_IOPAD(0x1c4, PIN_OUTPUT | MUX_MODE3) /* gpio22 */
+			OMAP4_IOPAD(0x1cc, PIN_OUTPUT | MUX_MODE3) /* gpio26 */
+		>;
+	};
+
 	i2c1_pins: pinmux-i2c1-pins {
 		pinctrl-single,pins = <
 			   OMAP4_IOPAD(0x122, PIN_INPUT_PULLUP | MUX_MODE0)	/* i2c1_scl */
@@ -527,6 +602,15 @@ OMAP4_IOPAD(0x1c8, PIN_OUTPUT | MUX_MODE3)  /* gpio_24 / WLAN_EN */
 	};
 };
 
+&omap4_pmx_wkup {
+	gpio1wk_hog_pins: pinmux-gpio1wk-hog-pins {
+		pinctrl-single,pins = <
+			OMAP4_IOPAD(0x68, PIN_INPUT_PULLDOWN | MUX_MODE3) /* gpio9 */
+			OMAP4_IOPAD(0x6a, PIN_INPUT | MUX_MODE3) /* gpio10 */
+		>;
+	};
+};
+
 &uart2 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&uart2_pins &bt_pins>;
-- 
2.39.5

[PATCH 4/4] ARM: dts: omap: omap4-epson-embt2ws: add GPIO expander

[Andreas Kemnade]

Define the GPIO expander which controls at least some camera gpios.

Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
---
 arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
index c8205ae89840..ecd727e65761 100644
--- a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
+++ b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
@@ -291,6 +291,19 @@ &i2c2 {
 
 	clock-frequency = <200000>;
 
+	/* is sometimes not available, research needed */
+	gpio_head: gpio@20 {
+		compatible = "ti,tca6408";
+		reg = <0x20>;
+		gpio-controller;
+		#gpio-cells = <2>;
+	};
+
+	/*
+	 * camera chip at 0x3c, available if <&gpio_head 1> high
+	 * and <&gpio_head 5> low
+	 */
+
 	/* at head/glasses */
 	mpu9150h: imu@68 {
 		compatible = "invensense,mpu9150";
-- 
2.39.5

Re: [PATCH 0/4] ARM: dts: omap: omap4-epson-embt2ws: misc gpio definitions

[Rob Herring (Arm)]

On Mon, 30 Sep 2024 23:30:04 +0200, Andreas Kemnade wrote:
> Bring the system into a more defined state and do not rely
> on things being initialized by bootloader.
> 
> Andreas Kemnade (4):
>   ARM: dts: omap: omap4-epson-embt2ws: define GPIO regulators
>   ARM: dts: omap: omap4-epson-embt2ws: wire up regulators
>   ARM: dts: omap: omap4-epson-embt2ws: add unknown gpio outputs
>   ARM: dts: omap: omap4-epson-embt2ws: add GPIO expander
> 
>  .../boot/dts/ti/omap/omap4-epson-embt2ws.dts  | 175 +++++++++++++++++-
>  1 file changed, 171 insertions(+), 4 deletions(-)
> 
> --
> 2.39.5
> 
> 
> 


My bot found new DTB warnings on the .dts files added or changed in this
series.

Some warnings may be from an existing SoC .dtsi. Or perhaps the warnings
are fixed by another series. Ultimately, it is up to the platform
maintainer whether these warnings are acceptable or not. No need to reply
unless the platform maintainer has comments.

If you already ran DT checks and didn't see these error(s), then
make sure dt-schema is up to date:

  pip3 install dtschema --upgrade


New warnings running 'make CHECK_DTBS=y ti/omap/omap4-epson-embt2ws.dtb' for 20240930213008.159647-1-andreas@kemnade.info:

arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dtb: serial@0: {'compatible': ['ti,omap4-uart'], 'reg': [[0, 256]], 'interrupts': [[0, 74, 4]], 'clock-frequency': 48000000, 'pinctrl-names': ['default'], 'pinctrl-0': [[115]], 'interrupts-extended': [[1, 0, 74, 4], [116, 260]], '$nodename': ['serial@0']} is valid under each of {'required': ['interrupts-extended']}, {'required': ['interrupts']}
	from schema $id: http://devicetree.org/schemas/serial/8250_omap.yaml#
arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dtb: serial@0: {'compatible': ['ti,omap4-uart'], 'reg': [[0, 256]], 'interrupts': [[0, 73, 4]], 'clock-frequency': 48000000, 'pinctrl-names': ['default'], 'pinctrl-0': [[118, 119]], 'interrupts-extended': [[1, 0, 73, 4], [116, 220]], 'bluetooth-gnss': {'compatible': ['ti,wl1283-st'], 'enable-gpios': [[120, 25, 0]], 'clocks': [[121, 1]], 'clock-names': ['ext_clock']}, '$nodename': ['serial@0']} is valid under each of {'required': ['interrupts-extended']}, {'required': ['interrupts']}
	from schema $id: http://devicetree.org/schemas/serial/8250_omap.yaml#

Re: [PATCH 1/4] ARM: dts: omap: omap4-epson-embt2ws: define GPIO regulators

[Roger Quadros]

On 01/10/2024 00:30, Andreas Kemnade wrote:
> To properly have things running after cold boot, define
> GPIO regulators. Naming is based on board file.
> 
> In the vendor kernel they are enabled in a function
> called bt2ws_dcdc_init() if the system is not booted just
> to charge the battery.
> 
> Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
> ---
>  .../boot/dts/ti/omap/omap4-epson-embt2ws.dts  | 73 +++++++++++++++++++
>  1 file changed, 73 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
> index 339e52ba3614..d6b0abba19f6 100644
> --- a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
> +++ b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
> @@ -29,6 +29,42 @@ backlight-right {
>  		power-supply = <&unknown_supply>;
>  	};
>  
> +	cb_v18: cb-v18 {

https://devicetree-specification.readthedocs.io/en/v0.3/devicetree-basics.html#generic-names-recommendation


So regulator@n
where n is some index if it can't be address.

> +		pinctrl-names = "default";
> +		pinctrl-0 = <&cb_v18_pins>;
> +		compatible = "regulator-fixed";
> +		regulator-name = "cb_v18";
> +		regulator-min-microvolt = <1800000>;
> +		regulator-max-microvolt = <1800000>;
> +		regulator-always-on;
> +		gpio = <&gpio1 28 GPIO_ACTIVE_HIGH>;
> +		enable-active-high;
> +	};
> +
> +	cb_v33: cb-v33 {
here

> +		pinctrl-names = "default";
> +		pinctrl-0 = <&cb_v33_pins>;
> +		compatible = "regulator-fixed";
> +		regulator-name = "cb_v33";
> +		regulator-min-microvolt = <3300000>;
> +		regulator-max-microvolt = <3300000>;
> +		regulator-always-on;
> +		gpio = <&gpio6 30 GPIO_ACTIVE_HIGH>;
> +		enable-active-high;
> +	};
> +
> +	cb-v50 {
here too

> +		pinctrl-names = "default";
> +		pinctrl-0 = <&cb_v50_pins>;
> +		compatible = "regulator-fixed";
> +		regulator-name = "cb_v50";
> +		regulator-min-microvolt = <5000000>;
> +		regulator-max-microvolt = <5000000>;
> +		regulator-always-on;
> +		gpio = <&gpio6 31 GPIO_ACTIVE_HIGH>;
> +		enable-active-high;
> +	};
> +
>  	chosen {
>  		stdout-path = &uart3;
>  	};
> @@ -46,6 +82,19 @@ key-lock {
>  		};
>  	};
>  
> +	lb_v50: lb-v50 {
and here as well

> +		/* required for many things at the head (probably indirectly) */
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&lb_v50_pins>;
> +		compatible = "regulator-fixed";
> +		regulator-name = "lb_v50";
> +		regulator-min-microvolt = <5000000>;
> +		regulator-max-microvolt = <5000000>;
> +		regulator-always-on;
> +		gpio = <&gpio1 27 GPIO_ACTIVE_HIGH>;
> +		enable-active-high;
> +	};
> +
>  	unknown_supply: unknown-supply {
>  		compatible = "regulator-fixed";
>  		regulator-name = "unknown";
> @@ -336,6 +385,24 @@ OMAP4_IOPAD(0x1ca, PIN_OUTPUT | MUX_MODE3) /* gpio25 */
>  		>;
>  	};
>  
> +	cb_v18_pins: pinmux-cb-v18-pins {
> +		pinctrl-single,pins = <
> +			OMAP4_IOPAD(0x1d0, PIN_OUTPUT | MUX_MODE3) /* gpio28 */
> +		>;
> +	};
> +
> +	cb_v33_pins: pinmux-cb-v33-pins {
> +		pinctrl-single,pins = <
> +			OMAP4_IOPAD(0x1d2, PIN_OUTPUT | MUX_MODE3) /* gpio190 */
> +		>;
> +	};
> +
> +	cb_v50_pins: pinmux-cb-v50-pins {
> +		pinctrl-single,pins = <
> +			OMAP4_IOPAD(0x1d4, PIN_OUTPUT | MUX_MODE3) /* gpio191 */
> +		>;
> +	};
> +
>  	gpio_keys_pins: pinmux-gpio-key-pins {
>  		pinctrl-single,pins = <
>  			OMAP4_IOPAD(0x56, PIN_INPUT_PULLUP | MUX_MODE3) /* gpio35 */
> @@ -387,6 +454,12 @@ OMAP4_IOPAD(0x005c, PIN_OUTPUT | MUX_MODE1)
>  		>;
>  	};
>  
> +	lb_v50_pins: pinmux-lb-v50-pins {
> +		pinctrl-single,pins = <
> +			OMAP4_IOPAD(0x1ce, PIN_OUTPUT | MUX_MODE3) /* gpio27 */
> +		>;
> +	};
> +
>  	mcbsp2_pins: pinmux-mcbsp2-pins {
>  		pinctrl-single,pins = <
>  			OMAP4_IOPAD(0x0f6, PIN_INPUT | MUX_MODE0)       /* abe_mcbsp2_clkx */

-- 
cheers,
-roger

Re: [PATCH 2/4] ARM: dts: omap: omap4-epson-embt2ws: wire up regulators

[Roger Quadros]

On 01/10/2024 00:30, Andreas Kemnade wrote:
> Wire up the regulators where usage is plausible. Do not
> wire them if purpose/usage is unclear like 5V for
> many things requiring lower voltages.
> 
> Signed-off-by: Andreas Kemnade <andreas@kemnade.info>

Reviewed-by: Roger Quadros <rogerq@kernel.org>

Re: [PATCH 2/4] ARM: dts: omap: omap4-epson-embt2ws: wire up regulators

[Roger Quadros]

On 01/10/2024 00:30, Andreas Kemnade wrote:
> Wire up the regulators where usage is plausible. Do not
> wire them if purpose/usage is unclear like 5V for
> many things requiring lower voltages.
> 
> Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
> ---
>  arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
> index d6b0abba19f6..cc1b6080bf95 100644
> --- a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
> +++ b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
> @@ -20,13 +20,13 @@ memory@80000000 {
>  	backlight-left {
>  		compatible = "pwm-backlight";
>  		pwms = <&twl_pwm 1 7812500>;
> -		power-supply = <&unknown_supply>;
> +		power-supply = <&lb_v50>;

This is probably wrong. I noticed this while reviewing patch 3.

you probably want to wire this to blc_l?

>  	};
>  
>  	backlight-right {
>  		compatible = "pwm-backlight";
>  		pwms = <&twl_pwm 0 7812500>;
> -		power-supply = <&unknown_supply>;
> +		power-supply = <&lb_v50>;

this one should be wired to blc_r?

>  	};
>  
>  	cb_v18: cb-v18 {
> @@ -95,11 +95,6 @@ lb_v50: lb-v50 {
>  		enable-active-high;
>  	};
>  
> -	unknown_supply: unknown-supply {
> -		compatible = "regulator-fixed";
> -		regulator-name = "unknown";
> -	};
> -
>  	wl12xx_pwrseq: wl12xx-pwrseq {
>  		compatible = "mmc-pwrseq-simple";
>  		clocks = <&twl 1>;
> @@ -308,6 +303,8 @@ mpu9150: imu@68 {
>  		pinctrl-0 = <&mpu9150_pins>;
>  		interrupt-parent = <&gpio2>;
>  		interrupt = <7 IRQ_TYPE_LEVEL_HIGH>;
> +		vddio-supply = <&cb_v18>;
> +		vdd-supply = <&cb_v33>;
>  		invensense,level-shifter;
>  	};
>  };

-- 
cheers,
-roger

Re: [PATCH 1/4] ARM: dts: omap: omap4-epson-embt2ws: define GPIO regulators

[Andreas Kemnade]

Am Fri, 4 Oct 2024 10:24:32 +0300
schrieb Roger Quadros <rogerq@kernel.org>:

> On 01/10/2024 00:30, Andreas Kemnade wrote:
> > To properly have things running after cold boot, define
> > GPIO regulators. Naming is based on board file.
> > 
> > In the vendor kernel they are enabled in a function
> > called bt2ws_dcdc_init() if the system is not booted just
> > to charge the battery.
> > 
> > Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
> > ---
> >  .../boot/dts/ti/omap/omap4-epson-embt2ws.dts  | 73
> > +++++++++++++++++++ 1 file changed, 73 insertions(+)
> > 
> > diff --git a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
> > b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts index
> > 339e52ba3614..d6b0abba19f6 100644 ---
> > a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts +++
> > b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts @@ -29,6 +29,42
> > @@ backlight-right { power-supply = <&unknown_supply>;
> >  	};
> >  
> > +	cb_v18: cb-v18 {  
> 
> https://devicetree-specification.readthedocs.io/en/v0.3/devicetree-basics.html#generic-names-recommendation
> 
> 
> So regulator@n
> where n is some index if it can't be address.
> 
No, no @n. The above link says: "If the node has no reg property, the
@unit-address must be omitted and the node-name alone differentiates
the node from other nodes at the same level in the tree." So
probably regulator-cb-v18.

Regards,
Andreas

Re: [PATCH 3/4] ARM: dts: omap: omap4-epson-embt2ws: add unknown gpio outputs

[Roger Quadros]

On 01/10/2024 00:30, Andreas Kemnade wrote:
> Set them to the state seen in a running system, initialized
> by vendor u-boot or kernel. Add line names where they are defined in the
> vendor kernel.
> gpio15 resets something in the display, otherwise meaning of the
> gpios is not known.
> 
> Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
> ---
>  .../boot/dts/ti/omap/omap4-epson-embt2ws.dts  | 84 +++++++++++++++++++
>  1 file changed, 84 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
> index cc1b6080bf95..c8205ae89840 100644
> --- a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
> +++ b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
> @@ -115,6 +115,65 @@ wl12xx_vmmc: wl12xx-vmmc {
>  	};
>  };
>  > +&gpio1 {
> +	pinctrl-names = "default";
> +	pinctrl-0 = <&gpio1_hog_pins &gpio1wk_hog_pins>;
> +
> +	lb-reset-hog {
> +		gpio-hog;
> +		gpios = <9 GPIO_ACTIVE_HIGH>;
> +		output-low;
> +		line-name = "lb_reset";
> +	};

Just curious, what does lb stand for.

> +
> +	power-en-hog {
> +		gpio-hog;
> +		gpios = <10 GPIO_ACTIVE_HIGH>;
> +		output-high;
> +		line-name = "power_en";
> +	};
> +
> +	panel-power-en-hog {
> +		gpio-hog;
> +		gpios = <14 GPIO_ACTIVE_HIGH>;
> +		output-low;
> +		line-name = "panel_power_en";
> +	};

Is panel always enabled? I didn't see a panel driver
else it could be hooked to panel regulator?

> +
> +	blc-r-hog {
> +		gpio-hog;
> +		gpios = <17 GPIO_ACTIVE_HIGH>;
> +		output-low;
> +		line-name = "blc_r";
> +	};

this should be modeled as a gpio regulator and paried to backlight left?

> +
> +	blc-l-hog {
> +		gpio-hog;
> +		gpios = <16 GPIO_ACTIVE_HIGH>;
> +		output-low;
> +		line-name = "blc_l";
> +	};


this should be modeled as a gpio regulator and paried to backlight right?

> +
> +	high-hog {
> +		gpio-hog;
> +		gpios = <15 GPIO_ACTIVE_HIGH /* maybe dsi to dpi chip reset? */
> +			 21 GPIO_ACTIVE_HIGH
> +			 26 GPIO_ACTIVE_HIGH>;
> +		output-high;
> +		line-name = "unknown-high";
> +	};
> +
> +	low-hog {
> +		gpio-hog;
> +		gpios = <18 GPIO_ACTIVE_HIGH
> +			 19 GPIO_ACTIVE_HIGH
> +			 20 GPIO_ACTIVE_HIGH
> +			 22 GPIO_ACTIVE_HIGH>;
> +		output-low;
> +		line-name = "unknown-low";
> +	};

These are probably OK as we don't know their actual function.

> +};
> +
>  &i2c1 {
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&i2c1_pins>;
> @@ -406,6 +465,22 @@ OMAP4_IOPAD(0x56, PIN_INPUT_PULLUP | MUX_MODE3) /* gpio35 */
>  		>;
>  	};
>  
> +	gpio1_hog_pins: pinmux-gpio1-hog-pins {
> +		pinctrl-single,pins = <
> +			OMAP4_IOPAD(0x1b4, PIN_OUTPUT | MUX_MODE3) /* gpio14 */
> +			OMAP4_IOPAD(0x1b8, PIN_OUTPUT | MUX_MODE3) /* gpio16 */
> +			OMAP4_IOPAD(0x1ba, PIN_OUTPUT | MUX_MODE3) /* gpio17 */
> +
> +			OMAP4_IOPAD(0x1b6, PIN_OUTPUT | MUX_MODE3) /* gpio15 */
> +			OMAP4_IOPAD(0x1bc, PIN_OUTPUT | MUX_MODE3) /* gpio18 */
> +			OMAP4_IOPAD(0x1be, PIN_OUTPUT | MUX_MODE3) /* gpio19 */
> +			OMAP4_IOPAD(0x1c0, PIN_OUTPUT | MUX_MODE3) /* gpio20 */
> +			OMAP4_IOPAD(0x1c2, PIN_OUTPUT | MUX_MODE3) /* gpio21 */
> +			OMAP4_IOPAD(0x1c4, PIN_OUTPUT | MUX_MODE3) /* gpio22 */
> +			OMAP4_IOPAD(0x1cc, PIN_OUTPUT | MUX_MODE3) /* gpio26 */
> +		>;
> +	};
> +
>  	i2c1_pins: pinmux-i2c1-pins {
>  		pinctrl-single,pins = <
>  			   OMAP4_IOPAD(0x122, PIN_INPUT_PULLUP | MUX_MODE0)	/* i2c1_scl */
> @@ -527,6 +602,15 @@ OMAP4_IOPAD(0x1c8, PIN_OUTPUT | MUX_MODE3)  /* gpio_24 / WLAN_EN */
>  	};
>  };
>  
> +&omap4_pmx_wkup {
> +	gpio1wk_hog_pins: pinmux-gpio1wk-hog-pins {
> +		pinctrl-single,pins = <
> +			OMAP4_IOPAD(0x68, PIN_INPUT_PULLDOWN | MUX_MODE3) /* gpio9 */
> +			OMAP4_IOPAD(0x6a, PIN_INPUT | MUX_MODE3) /* gpio10 */
> +		>;
> +	};
> +};
> +
>  &uart2 {
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&uart2_pins &bt_pins>;

-- 
cheers,
-roger

Re: [PATCH 1/4] ARM: dts: omap: omap4-epson-embt2ws: define GPIO regulators

[Roger Quadros]

On 04/10/2024 10:41, Andreas Kemnade wrote:
> Am Fri, 4 Oct 2024 10:24:32 +0300
> schrieb Roger Quadros <rogerq@kernel.org>:
> 
>> On 01/10/2024 00:30, Andreas Kemnade wrote:
>>> To properly have things running after cold boot, define
>>> GPIO regulators. Naming is based on board file.
>>>
>>> In the vendor kernel they are enabled in a function
>>> called bt2ws_dcdc_init() if the system is not booted just
>>> to charge the battery.
>>>
>>> Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
>>> ---
>>>  .../boot/dts/ti/omap/omap4-epson-embt2ws.dts  | 73
>>> +++++++++++++++++++ 1 file changed, 73 insertions(+)
>>>
>>> diff --git a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
>>> b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts index
>>> 339e52ba3614..d6b0abba19f6 100644 ---
>>> a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts +++
>>> b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts @@ -29,6 +29,42
>>> @@ backlight-right { power-supply = <&unknown_supply>;
>>>  	};
>>>  
>>> +	cb_v18: cb-v18 {  
>>
>> https://devicetree-specification.readthedocs.io/en/v0.3/devicetree-basics.html#generic-names-recommendation
>>
>>
>> So regulator@n
>> where n is some index if it can't be address.
>>
> No, no @n. The above link says: "If the node has no reg property, the
> @unit-address must be omitted and the node-name alone differentiates
> the node from other nodes at the same level in the tree." So
> probably regulator-cb-v18.

Yes, I agree.

-- 
cheers,
-roger

Re: [PATCH 2/4] ARM: dts: omap: omap4-epson-embt2ws: wire up regulators

[Andreas Kemnade]

Am Fri, 4 Oct 2024 10:38:22 +0300
schrieb Roger Quadros <rogerq@kernel.org>:

> On 01/10/2024 00:30, Andreas Kemnade wrote:
> > Wire up the regulators where usage is plausible. Do not
> > wire them if purpose/usage is unclear like 5V for
> > many things requiring lower voltages.
> > 
> > Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
> > ---
> >  arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts | 11 ++++-------
> >  1 file changed, 4 insertions(+), 7 deletions(-)
> > 
> > diff --git a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
> > b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts index
> > d6b0abba19f6..cc1b6080bf95 100644 ---
> > a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts +++
> > b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts @@ -20,13
> > +20,13 @@ memory@80000000 { backlight-left {
> >  		compatible = "pwm-backlight";
> >  		pwms = <&twl_pwm 1 7812500>;
> > -		power-supply = <&unknown_supply>;
> > +		power-supply = <&lb_v50>;  
> 
> This is probably wrong. I noticed this while reviewing patch 3.
> 
> you probably want to wire this to blc_l?
> 
No idea was blc_l is. I did not find any code handling blc_l.
looking at the vendor kernel:

$ grep -R BLC_L_GPIO *
arch/arm/mach-omap2/board-bt2ws.c:#define BLC_L_GPIO
16	/* LB LED GPIO */ arch/arm/mach-omap2/board-bt2ws.c:
{BLC_L_GPIO,   GPIOF_OUT_INIT_LOW,  "gpio_blc_l"   },
arch/arm/mach-omap2/board-bt2ws.c:	gpio_export(BLC_L_GPIO, 0);
arch/arm/mach-omap2/board-bt2ts.c:#define BLC_L_GPIO
16	/* LB LED GPIO */ arch/arm/mach-omap2/board-bt2ts.c:
{BLC_L_GPIO,   GPIOF_OUT_INIT_LOW,  "gpio_blc_l"   },
arch/arm/mach-omap2/board-bt2ts.c:	gpio_export(BLC_L_GPIO, 0);

These two gpios are exported. But they seem not to influence
backlight in any way. I just tested again to make sure. Maybe it is just
a leftover from earlier board revisions.

> >  	};
> >  
> >  	backlight-right {
> >  		compatible = "pwm-backlight";
> >  		pwms = <&twl_pwm 0 7812500>;
> > -		power-supply = <&unknown_supply>;
> > +		power-supply = <&lb_v50>;  
> 
> this one should be wired to blc_r?
>
Same as with blc_l.
$ grep -R BLC_R_GPIO *
arch/arm/mach-omap2/board-bt2ws.c:#define BLC_R_GPIO
17	/* LB LED GPIO */ arch/arm/mach-omap2/board-bt2ws.c:
{BLC_R_GPIO,   GPIOF_OUT_INIT_LOW,  "gpio_blc_r"   },
arch/arm/mach-omap2/board-bt2ws.c:	gpio_export(BLC_R_GPIO, 0);
arch/arm/mach-omap2/board-bt2ts.c:#define BLC_R_GPIO
17	/* LB LED GPIO */ arch/arm/mach-omap2/board-bt2ts.c:
{BLC_R_GPIO,   GPIOF_OUT_INIT_LOW,  "gpio_blc_r"   },
arch/arm/mach-omap2/board-bt2ts.c:	gpio_export(BLC_R_GPIO, 0);

Regards,
Andreas

Re: [PATCH 2/4] ARM: dts: omap: omap4-epson-embt2ws: wire up regulators

[Roger Quadros]

On 04/10/2024 12:01, Andreas Kemnade wrote:
> Am Fri, 4 Oct 2024 10:38:22 +0300
> schrieb Roger Quadros <rogerq@kernel.org>:
> 
>> On 01/10/2024 00:30, Andreas Kemnade wrote:
>>> Wire up the regulators where usage is plausible. Do not
>>> wire them if purpose/usage is unclear like 5V for
>>> many things requiring lower voltages.
>>>
>>> Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
>>> ---
>>>  arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts | 11 ++++-------
>>>  1 file changed, 4 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
>>> b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts index
>>> d6b0abba19f6..cc1b6080bf95 100644 ---
>>> a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts +++
>>> b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts @@ -20,13
>>> +20,13 @@ memory@80000000 { backlight-left {
>>>  		compatible = "pwm-backlight";
>>>  		pwms = <&twl_pwm 1 7812500>;
>>> -		power-supply = <&unknown_supply>;
>>> +		power-supply = <&lb_v50>;  
>>
>> This is probably wrong. I noticed this while reviewing patch 3.
>>
>> you probably want to wire this to blc_l?
>>
> No idea was blc_l is. I did not find any code handling blc_l.
> looking at the vendor kernel:
> 
> $ grep -R BLC_L_GPIO *
> arch/arm/mach-omap2/board-bt2ws.c:#define BLC_L_GPIO
> 16	/* LB LED GPIO */ arch/arm/mach-omap2/board-bt2ws.c:
> {BLC_L_GPIO,   GPIOF_OUT_INIT_LOW,  "gpio_blc_l"   },
> arch/arm/mach-omap2/board-bt2ws.c:	gpio_export(BLC_L_GPIO, 0);
> arch/arm/mach-omap2/board-bt2ts.c:#define BLC_L_GPIO
> 16	/* LB LED GPIO */ arch/arm/mach-omap2/board-bt2ts.c:
> {BLC_L_GPIO,   GPIOF_OUT_INIT_LOW,  "gpio_blc_l"   },
> arch/arm/mach-omap2/board-bt2ts.c:	gpio_export(BLC_L_GPIO, 0);
> 
> These two gpios are exported. But they seem not to influence
> backlight in any way. I just tested again to make sure. Maybe it is just
> a leftover from earlier board revisions.

OK. you could then leave it as it is now.

> 
>>>  	};
>>>  
>>>  	backlight-right {
>>>  		compatible = "pwm-backlight";
>>>  		pwms = <&twl_pwm 0 7812500>;
>>> -		power-supply = <&unknown_supply>;
>>> +		power-supply = <&lb_v50>;  
>>
>> this one should be wired to blc_r?
>>
> Same as with blc_l.
> $ grep -R BLC_R_GPIO *
> arch/arm/mach-omap2/board-bt2ws.c:#define BLC_R_GPIO
> 17	/* LB LED GPIO */ arch/arm/mach-omap2/board-bt2ws.c:
> {BLC_R_GPIO,   GPIOF_OUT_INIT_LOW,  "gpio_blc_r"   },
> arch/arm/mach-omap2/board-bt2ws.c:	gpio_export(BLC_R_GPIO, 0);
> arch/arm/mach-omap2/board-bt2ts.c:#define BLC_R_GPIO
> 17	/* LB LED GPIO */ arch/arm/mach-omap2/board-bt2ts.c:
> {BLC_R_GPIO,   GPIOF_OUT_INIT_LOW,  "gpio_blc_r"   },
> arch/arm/mach-omap2/board-bt2ts.c:	gpio_export(BLC_R_GPIO, 0);
> 
> Regards,
> Andreas

-- 
cheers,
-roger

Re: [PATCH 3/4] ARM: dts: omap: omap4-epson-embt2ws: add unknown gpio outputs

[Andreas Kemnade]

Am Fri, 4 Oct 2024 10:53:57 +0300
schrieb Roger Quadros <rogerq@kernel.org>:

> On 01/10/2024 00:30, Andreas Kemnade wrote:
> > Set them to the state seen in a running system, initialized
> > by vendor u-boot or kernel. Add line names where they are defined
> > in the vendor kernel.
> > gpio15 resets something in the display, otherwise meaning of the
> > gpios is not known.
> > 
> > Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
> > ---
> >  .../boot/dts/ti/omap/omap4-epson-embt2ws.dts  | 84
> > +++++++++++++++++++ 1 file changed, 84 insertions(+)
> > 
> > diff --git a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts
> > b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts index
> > cc1b6080bf95..c8205ae89840 100644 ---
> > a/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts +++
> > b/arch/arm/boot/dts/ti/omap/omap4-epson-embt2ws.dts @@ -115,6
> > +115,65 @@ wl12xx_vmmc: wl12xx-vmmc { };
> >  };  
> >  > +&gpio1 {  
> > +	pinctrl-names = "default";
> > +	pinctrl-0 = <&gpio1_hog_pins &gpio1wk_hog_pins>;
> > +
> > +	lb-reset-hog {
> > +		gpio-hog;
> > +		gpios = <9 GPIO_ACTIVE_HIGH>;
> > +		output-low;
> > +		line-name = "lb_reset";
> > +	};  
> 
> Just curious, what does lb stand for.
> 
me too. Maybe b is the same as in cb 

static struct gpio bt2ws_lb_gpios[] = {
        {BLC_L_GPIO,   GPIOF_OUT_INIT_LOW,  "gpio_blc_l"   },
        {BLC_R_GPIO,   GPIOF_OUT_INIT_LOW,  "gpio_blc_r"   },
        {LB_RESET_GPIO,GPIOF_OUT_INIT_LOW,  "gpio_lb_reset"},
        {POWER_EN_GPIO,GPIOF_OUT_INIT_HIGH, "gpio_power_en"},
        {PANEL_POWER_EN_GPIO,GPIOF_OUT_INIT_LOW, "gpio_panel_power_en"},
};

That is what is in the vendor kernel and matches 

> > +
> > +	power-en-hog {
> > +		gpio-hog;
> > +		gpios = <10 GPIO_ACTIVE_HIGH>;
> > +		output-high;
> > +		line-name = "power_en";
> > +	};
> > +
> > +	panel-power-en-hog {
> > +		gpio-hog;
> > +		gpios = <14 GPIO_ACTIVE_HIGH>;
> > +		output-low;
> > +		line-name = "panel_power_en";
> > +	};  
> 
> Is panel always enabled? I didn't see a panel driver
> else it could be hooked to panel regulator?
> 
Panels are behind two dsi to dpi converters.
I have a driver. At the moment, I boot into vendor
v3.0 kernel, reprogram boot order, warm reboot into mainline u-boot +
kernel to get display working. I can read registers via dsi at least
after blanking the panel for the first time. Blanking/unblanking seems
to work.
With a low pulse on gpio15 I can reset something in the display which
the vendor kernel can recover from but not my mainline driver. Then no
communication with the display seem to work.

About gpio 10/14 I know only the name (from the possibly kernel sources
and matching /sys/kernel/debug/gpio). And that knowledge I want to
forward into the formal hardware description, the device tree.

$ grep -R PANEL_POWER_EN *
arch/arm/mach-omap2/board-bt2ws.c:
{PANEL_POWER_EN_GPIO,GPIOF_OUT_INIT_LOW, "gpio_panel_power_en"},
arch/arm/mach-omap2/board-bt2ts.c:
{PANEL_POWER_EN_GPIO,GPIOF_OUT_INIT_LOW, "gpio_panel_power_en"},
include/video/omap-panel-bt2.h:#define PANEL_POWER_EN_GPIO 14	// GPIO

But I did not get the supposed vendor kernel to fully boot. I have the verdict
that I do not have the exact sources of the kernel which is running.
I also did not notice any change in behaviour when toggling these gpios.
So either they are a leftover from another board revision or something
gets supplied by some parasitic ways.

I think the best is to explain the situation more in the comments.
What is a bit difficult is here is that there is something done in the m3
processors but apparently nothing vital to having display output (tried
with an initrd without any m3 firmware), probably
doing something camera-related, so the kernel sources do not give a full
picture of the hardware anyways.

BTW: do you know how to best trace gpio changes done by the vendor kernel
without recompiling it? I managed to write a module deviating the master_xfre
function for i2c to log things.

> > +
> > +	blc-r-hog {
> > +		gpio-hog;
> > +		gpios = <17 GPIO_ACTIVE_HIGH>;
> > +		output-low;
> > +		line-name = "blc_r";
> > +	};  
> 
> this should be modeled as a gpio regulator and paried to backlight
> left?
> 
Discussed in patch 2.

Regards,
Andreas