Re: [PATCH v7 1/3] dt-bindings: hwmon: Add adt7475 fan/pwm properties

[Guenter Roeck]

On Wed, May 28, 2025 at 09:18:37PM +0000, Chris Packham wrote:
> >> As I mentioned at the time the adt7475 is not currently pwm_chip so I
> >> need the ad-hoc parsing in that driver. I'd be happy to take you
> >> prototype patch for pwm/core.c and polish it although I don't really
> >> have a good way of testing it.
> > It's more the deviation of the default binding for PWMs that I don't
> > like than the ad-hoc parsing. Ideally the adt7475 would provide a
> > pwmchip (as the binding suggests) and the fan would be formalized as a

We are not going to force each fan controller driver to register as pwm chip
just because it provides a pwm value to control the fans - even more so since
this gets really ugly if the chip can be programmed to either provide a voltage
output or a pwm value to control fan speed. Maybe the next requirement is that
fan controllers supporting voltage output to control fan speeds are supposed
to register themselves as regulators. I really don't want to go there.

Those are _not_ pwm controllers. They are special-purpose fan controllers.
Forcing them into the pwm framework from devicetree perspective is bad enough,
but forcing them to register as pwm controllers is a step too far.

Guenter