Re: [PATCH 2/2] arm64: dts: imx8mp: Add support for Data Modul i.MX8M Plus eDM SBC

[Marek Vasut <marex@denx.de>]

On 1/1/23 05:00, Shawn Guo wrote:

[...]

>> +	panel: panel {
> 
> No compatible?

The compatible string is filled in by expansion module DT overlay, so no 
default compatible string in the panel node here. The panel interface is 
the same for all panels that can be atteched to this board, so the panel 
node is common for all DTOs and can be in the base DT.

>> +		backlight = <&backlight>;
>> +		power-supply = <&reg_panel_vcc>;
>> +		/* Disabled by default, unless display board plugged in. */
>> +		status = "disabled";
>> +	};
>> +
>> +	reg_panel_vcc: regulator-panel-vcc {
>> +		compatible = "regulator-fixed";
>> +		pinctrl-names = "default";
>> +		pinctrl-0 = <&pinctrl_panel_vcc_reg>;
>> +		regulator-name = "PANEL_VCC";
>> +		regulator-min-microvolt = <5000000>;
>> +		regulator-max-microvolt = <5000000>;
>> +		gpio = <&gpio3 6 0>;
> 
> GPIO_ACTIVE_HIGH?

No, the 0 is correct and you're not the first one to wonder about this 
oddity.

See drivers/gpio/gpiolib-of.c :

  203 /*
  204  * The regulator GPIO handles are specified such that the
  205  * presence or absence of "enable-active-high" solely controls
  206  * the polarity of the GPIO line. Any phandle flags must
  207  * be actively ignored.
  208  */
  209 #if IS_ENABLED(CONFIG_REGULATOR_FIXED_VOLTAGE)
  210     { "regulator-fixed",   "gpios",    "enable-active-high" },
  211     { "regulator-fixed",   "gpio",     "enable-active-high" },

[...]