Re: [PATCH v2 3/4] ARM: dts: omap: omap4-epson-embt2ws: add unknown gpio outputs

[Roger Quadros <rogerq@kernel.org>]

On 10/10/2024 15:29, 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  | 92 +++++++++++++++++++
>  1 file changed, 92 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 7684868a2eed..983a21d95db3 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 +115,73 @@ 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";
> +	};

As GPIO 9 and 10 come form the Wake-up domain, my guess is 
they are used as wake-up input source. Reset button / Power off/wake button?
From pinmux they seem to be Input. So why do we need to force them to a
certain output state?
Can you please confirm if everything works as usual without this hog?

We could still give the GPIO a name without the hog right?
maybe user-space is interested in the state.

> +
> +	/*
> +	 * Name taken from vendor kernel but no evidence of actual usage found
> +	 * nor what it really controls.
> +	 */
> +	panel-power-en-hog {
> +		gpio-hog;
> +		gpios = <14 GPIO_ACTIVE_HIGH>;
> +		output-low;
> +		line-name = "panel_power_en";
> +	};
> +
> +	/*
> +	 * These two are exported to sysfs in vendor kernel, usage unknown,
> +	 * backlight state seems unrelated to these.
> +	 */
> +	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 +473,22 @@ 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 +610,15 @@ 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