Subject: Re: [RFC PATCH v3 0/2] hwmon: emc2305: Support configurable fan PWM at shutdown

From: Florin Leotescu <[email-masked]>
Date: Fri, 20 Mar 2026 15:52:01 +0200

On Tue, Mar 17, 2026 at 09:17:21AM -0700, Guenter Roeck wrote:
> On 3/12/26 07:43, [email-masked] wrote:
> > From: Florin Leotescu <[email-masked]>
> > 
> > This series adds support for configuring the fan PWM duty cycle applied
> > during system shutdown for the EMC2305 fan controller.
> > 
> > Some platforms require fans to transition to a predefined safe state
> > during shutdown or reboot handoff until firmware or the next boot stage
> > reconfigures the controller.
> > 
> > The new optional Device Tree property "fan-shutdown-percent" allows the
> > shutdown PWM duty cycle to be configured per fan output.
> > 
> > Changes in v3:
> > - Rebased on current upstream
> > - Dropped already upstreamed of_node_put(child) fix
> > Changes in v2:
> > - Address feedback from Guenter Roeck
> > - Make shutdown behavior configurable via Device Tree
> > - Add optional fan-shutdown-percent property
> > - Apply shutdown PWM only for channels defining the property
> > 
> > Florin Leotescu (2):
> >    dt-bindings: hwmon: emc2305: Add fan-shutdown-percent property
> >    hwmon: emc2305: Support configurable fan PWM at shutdown
> > 
> >   .../bindings/hwmon/microchip,emc2305.yaml     |  8 +++++
> >   drivers/hwmon/emc2305.c                       | 34 +++++++++++++++++++
> >   2 files changed, 42 insertions(+)
> > 
> AI review of series is here:
> 
> https://sashiko.dev/#/patchset/20260312144325.1311314-1-florin.leotescu%40oss.nxp.com
> 
> Please take a look.
>
Hi Guenter,

Thanks for pointing this out.
You're right, since the pwm_shutdown array is zero-initialized by devm_kzalloc,
the channels that are not explicitly configured, will be treated as valid
and written as 0 during shutdown. I'll fix it in next revision.

> Thanks,
> Guenter