On Mon, Dec 20, 2021 at 10:44:35AM +0100, Sascha Hauer wrote:

Well, all true and on one specific board the regulator is indeed not
optional. However, on all other power domains that don't need a
regulator and all other boards and all other SoCs this driver is used we
now get:

This seems unlikely to be board specific, if the chip requires power the
chip requires power.  If there are power domains that don't take
external supplies then they shouldn't be requesting any regulators and
should be fixed.

[    0.185588] rk-power-domain rk-power-domain.8: supply power not found, using dummy regulator

It seems vanishingly unlikely that the SoC takes a single supply called
"power" shared by everything in the SoC but that is what the code
appears to be requesting - the power domains should be requesting the
supplies they actually use, and as ever the supplies should be named
such that someone looking at the schematic can hook them up.  The
general recommendation is to use the names used in the datasheet.

I wonder if devm_regulator_get() is really the right function here. Or
should the message be dropped?

No, the issue is that the client driver is badly written and needs to be
fixed.  In general it's probably better to have error handling than not.
If you're getting lots of warnings about problems it's probably due to
there being problems.