Re: [RFC PATCH v2 1/2] dt-bindings: hwmon: emc2305: Add fan-shutdown-percent property

[Florin Leotescu]

On Thu, Mar 12, 2026 at 05:37:51PM +0000, Conor Dooley wrote:
> On Thu, Mar 12, 2026 at 02:22:47PM +0200, florin.leotescu@xxxxxxxxxxx wrote:
> > From: Florin Leotescu <florin.leotescu@xxxxxxx>
> > 
> > The EMC2305 fan controller supports multiple independent PWM fan
> > outputs. Some systems require fans to enter a defined safe state
> > during system shutdown or reboot handoff, until firmware or the next
> > boot stage reconfigures the controller.
> > 
> > Add an optional "fan-shutdown-percent" property to fan child nodes
> > allowing the shutdown fan speed to be configured per fan output.
> > 
> > Signed-off-by: Florin Leotescu <florin.leotescu@xxxxxxx>
> > ---
> >  .../devicetree/bindings/hwmon/microchip,emc2305.yaml      | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml b/Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml
> > index d3f06ebc19fa..7bcadfab9fc4 100644
> > --- a/Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml
> > +++ b/Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml
> > @@ -54,6 +54,12 @@ patternProperties:
> >            The fan number used to determine the associated PWM channel.
> >          maxItems: 1
> >  
> > +      fan-shutdown-percent:
> > +        description:
> > +          Fan RPM in percent set during shutdown.
> 
> This sounds like something generic, that other devices might need and
> should be in fan-common.yaml?
>
Thanks for the feedback.

The property name was reused from pwm-fan.yaml where it already exists
with the same meaning. I kept it local to minimize the scope of the change.

However, if you prefer it to be modelled as a common property, I can adjust it in the next revision.

> > +        minimum: 0
> > +        maximum: 100
> > +
> >      required:
> >        - reg
> >  
> > @@ -80,12 +86,14 @@ examples:
> >              fan@0 {
> >                  reg = <0x0>;
> >                  pwms = <&fan_controller 26000 PWM_POLARITY_INVERTED 1>;
> > +                fan-shutdown-percent = <100>;
> >                  #cooling-cells = <2>;
> >              };
> >  
> >              fan@1 {
> >                  reg = <0x1>;
> >                  pwms = <&fan_controller 26000 0 1>;
> > +                fan-shutdown-percent = <50>;
> >                  #cooling-cells = <2>;
> >              };
> >  
> > -- 
> > 2.34.1
> >