[PATCH v1 0/5] power: domain: Add driver for a PM domain provider which controls

[Geert Uytterhoeven]

Hi Rob,

On Mon, Jun 13, 2022 at 9:15 PM Rob Herring <robh at kernel.org> wrote:
> On Thu, Jun 09, 2022 at 05:08:46PM +0200, Max Krummenacher wrote:
> > From: Max Krummenacher <max.krummenacher at toradex.com>
> >
> > its power enable by using a regulator.
> >
> > The currently implemented PM domain providers are all specific to
> > a particular system on chip.
>
> Yes, power domains tend to be specific to an SoC... 'power-domains' is
> supposed to be power islands in a chip. Linux 'PM domains' can be
> anything...

> > This allows to use the "regulator-pm-pd" driver with an arbitrary
> > device just by adding the 'power-domains' property to the devices
> > device tree node. However the device's dt-bindings schema likely does
> > not allow the property 'power-domains'.
> > One way to solve this would be to allow 'power-domains' globally
> > similarly how 'status' and other common properties are allowed as
> > implicit properties.
>
> No. For 'power-domains' bindings have to define how many there are and
> what each one is.

IMO "power-domains" are an integration feature, i.e. orthogonal to the
actual device that is part of the domain.  Hence the "power-domains"
property may appear everywhere.

It is actually the same for on-chip devices, as an IP core may be
reused on a new SoC that does have power or clock domains.  For
these, we managed to handle that fine because most devices do have
some form of family- or SoC-specific compatible values to control if
the power-domains property can be present/is required or not.

But for off-chip devices, the integrator (board designed) can do
whatever he wants.  Off-chip devices do have the advantage that it
is usually well documented which power supply (if there are multiple)
serves which purpose, which is not always clear for on-chip devices.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds