Re: [PATCH v4 3/3] arm64: dts: imx95: Add support for Data Modul i.MX95 eDM SBC

[Frank Li <Frank.li@oss.nxp.com>]

On Sun, Sep 20, 2026 at 07:05:58PM +0200, Marek Vasut wrote:
> On 9/18/26 3:58 PM, Frank Li wrote:
>
> Hello Frank,
>
> > > > > > > > +	reg_panel_vcc: regulator-panel-vcc {
> > > > > > > > +		compatible = "regulator-fixed";
> > > > > > > > +		regulator-min-microvolt = <3300000>;
> > > > > > > > +		regulator-max-microvolt = <3300000>;
> > > > > > > > +		regulator-name = "PANEL_VCC";
> > > > > > > > +		gpios = <&i2c2_gpio_expander_20 17 0>;
> > > > > >
> > > > > > gpio third arg 0, means GPIO_ACTIVE_HIGH
> > > > > >
> > > > > > 	so need enable-active-high
> > > > > >
> > > > > > if your boards have invertor should use GPIO_ACTIVE_LOW
> > > > >
> > > > > I already went through all that, please see "Re: [PATCH 3/3] arm64: dts:
> > > > > imx95: Add support for Data Modul i.MX95 eDM SBC" .
> > > >
> > > > at https://lore.kernel.org/imx/f4dbeaac-ab10-4980-9fc5-533907be223c@nabladev.com/
> > > >
> > > > <&i2c2_gpio_expander_20 17 0>;
> > > >                              ^
> > > >
> > > > 0 should use predefine MACRO, after I check 0 means GPIO_ACTIVE_HIGH.
> > > >
> > > > so need enable-active-high for regulator.
> > >
> > > This is extended via a DTO, so no, I must not use a macro because I do not
> > > know the polarity of this signal, that is why there is 0 here.
> > >
> > > The enable-active-high DT property must explicitly NOT be here, because the
> > > DTO can not remove properties from the base DT. Adding enable-active-high
> > > here would make the DTO unable to operate this signal as active-low .
> >
> >
> > But why DTO need update regulator-panel-vcc's gpio informaiton. I suppose
> > it is fixed when board design.
>
> It is just a GPIO, it can have either polarity depending on the regulator
> that it controls.

Understand, But the problem is why polarity change after board design?

If reg_panel_vcc is on added on boards,  should it be in dtso file also to
match your hardware design correctly?

Frank

>
> --
> Best regards,
> Marek Vasut