Re: [PATCH 2/2] regulator: pwm-regulator: Revert "Add validity checks in continuous .get_voltage"

[Mark Brown <broonie@kernel.org>]

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On Fri, Nov 06, 2026 at 10:45:31PM +0100, Martin Blumenstingl wrote:
> On Fri, Nov 6, 2026 at 2:46 PM Mark Brown <broonie@kernel.org> wrote:
> > On Fri, Nov 06, 2026 at 01:59:56PM +0100, Mike Looijmans wrote:

> > > The core, and in particular the machine_constraints_voltage() method,
> > > expects the regulator to report what the current setting is, even if that
> > > is outside the allowed range. The core will then bring the voltage into
> > > that range. It cannot do that if the regulator refuses to return its
> > > setting, and causes probe() to fail for a pwm-regulator when it has
> > > restrictions to the PWM range with messages like:

...

> > > Besides that, regulator_get_voltage() is not supposed to return any
> > > state information, as is mentioned in the API documentation.
> according to include/linux/regulator/driver.h:

>  * @get_voltage: Return the currently configured voltage for the regulator;
>  *                   return -ENOTRECOVERABLE if regulator can't be read at
>  *                   bootup and hasn't been set yet.

> Can you please specify which API documentation you are referring to?

> I believe back when this change was authored it didn't make a
> difference on my board (but made sense based on review feedback).
> So I'm not against reverting as long as we have a proper explanation
> why the original patch is incorrect.

The PWM driver is a bit weird here since everything is very software
defined.  If the regulator is disabled and the state that the software
will apply on enable is known then it should return a value, if we have
no idea what the hardware will do on enable then we can't safely say
what the value that will be provided is.

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