Re: [PATCH 2/5] ARM: dts: add Samsung's exynos4412-based p4note boards

[Martin Juecker <martin.juecker@gmail.com>]

On Tue, Oct 27, 2020 at 09:17:51AM +0100, Krzysztof Kozlowski wrote:
> On Tue, Oct 27, 2020 at 12:27:09AM +0100, Martin Juecker wrote:
> > > > +
> > > > +	max77686: max77686_pmic@9 {
> > > > +		compatible = "maxim,max77686";
> > > > +		interrupt-parent = <&gpx0>;
> > > > +		interrupts = <7 IRQ_TYPE_NONE>;
> > > > +		pinctrl-0 = <&max77686_irq>;
> > > > +		pinctrl-names = "default";
> > > > +		reg = <0x09>;
> > > > +		#clock-cells = <1>;
> > > > +
> > > > +		voltage-regulators {
> > > 
> > > Just "regulators" and no empty line after this.
> > > 
> > > You should define all regulators here. If some are unknown, keep the
> > > min-max the same as in driver.
> > > 
> > 
> > I used the driver to read all the voltages, it also reads values for
> > the LDOs that are not defined in the DT, so I have values for all of
> > them setup by the bootloader. What I don't know is their name and what
> > they are used for. Interestingly apart from two LDOs, the voltages did
> > match exactly with those from the midas DT, so it could be very
> > similar. The two non-matching were only off by 0.1V. How should I go
> > about this?
> 
> Actually, let's skip the constraints (min-max) for unknown regulators.
> Just add the entries with generic names, like:
> arch/arm/boot/dts/exynos5410-odroidxu.dts
> 
> I would not put here min-max constraints from bootloader because pretty
> often it has only an initial setup for specific frequency - just to make
> it booting.
> 
> If you have the constraints (min-max, always on) from vendor sources,
> you could add them.
> 
> Best regards,
> Krzysztof

As all the missing regulators are not defined in the vendor sources, I
have no constraints to work with.

What I noticed when all the LDOs are defined, the device reboot
behaviour is different. Instead of the usual 1-2 seconds for screen off
and on again, it's now more like 10 seconds.

Cheers
Martin