Re: [PATCH 1/3] arm64: dts: mediatek: asurada: Add display regulators

[AngeloGioacchino Del Regno]

Il 21/09/22 15:48, Nícolas F. R. A. Prado ha scritto:
> On Fri, Sep 09, 2022 at 09:46:33AM +0200, AngeloGioacchino Del Regno wrote:
> > Il 08/09/22 19:11, Nícolas F. R. A. Prado ha scritto:
> > > Add the regulators present on the Asurada platform that are used to
> > > power the internal and external displays.
> > >
> > > Signed-off-by: Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx>
> > >
> > > ---
> > >
> > >    .../boot/dts/mediatek/mt8192-asurada.dtsi     | 114 ++++++++++++++++++
> > >    1 file changed, 114 insertions(+)
> > >
> > > diff --git a/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi b/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi
> > > index 4b314435f8fd..1d99e470ea1a 100644
> > > --- a/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi
> > > +++ b/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi
> >
> > ..snip..
> >
> > > @@ -56,6 +116,18 @@ pp3300_ldo_z: regulator-3v3-z {
> > >    		vin-supply = <&ppvar_sys>;
> > >    	};
> >
> > Can you please add a comment here advertising that this regulator
> > will not only provide power to the MIPI bridge, but *also* to the
> > display panel itself?
> >
> > This is to make sure that everyone understands what's going on, and
> > also that we ourselves don't forget about that.
> >
> > Probably something like:
> > /* pp3300_mipibrdg also enables pp3300_panel */
> >
> > I would then propose to add a "regulator-fixed" that has no GPIO
> > but with vin-supply as this one.
> >
> > pp3300_panel: regulator-3v3-panel {
> > 	compatible = "regulator-fixed";
> > 	regulator-name = "pp3300_panel";
> > 	regulator-min-microvolt = <3300000>;
> > 	regulator-max-microvolt = <3300000>;
> >
> > 	vin-supply = <&pp3300_mipibrdg>;
> > };
> >
> > I would also test assigning this regulator to the panel node, as this
> > will make sure to cover future corner cases (think about PM suspend/resume).
> >
> > P.S.: If you add the pp3300_panel regulator-fixed with that vin-supply,
> >        maybe the proposed comment would become a bit overkill. Your choice!
>
> Hi Angelo,
>
> thanks for the feedback.
>
> I think the current layout makes more sense based on my understanding of the
> power routing here: a single power line output by the pp3300_mipibrdg regulator
> powers both the ANX chip as well as the panel. So I'm going to keep it the way
> it is for now. If there are any other concerns please let me know.

As we discussed, I agree on this decision. Please go on.

Cheers!

> Thanks,
> Nícolas
>
> > Cheers,
> > Angelo
> >
> > > +	pp3300_mipibrdg: regulator-3v3-mipibrdg {
> > > +		compatible = "regulator-fixed";
> > > +		regulator-name = "pp3300_mipibrdg";
> > > +		pinctrl-names = "default";
> > > +		pinctrl-0 = <&pp3300_mipibrdg_en_pins>;
> > > +		regulator-min-microvolt = <3300000>;
> > > +		regulator-max-microvolt = <3300000>;
> > > +		enable-active-high;
> > > +		regulator-boot-on;
> > > +		gpio = <&pio 127 GPIO_ACTIVE_HIGH>;
> > > +	};
> > > +
> > >    	/* separately switched 3.3V power rail */
> > >    	pp3300_u: regulator-3v3-u {
> > >    		compatible = "regulator-fixed";