linux-kernel - Re: [PATCH 3/3] hwmon: (cros_ec) register fans into thermal framework cooling devices

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Message-ID: <aBGCB6_4XR4Z-vFI@google.com>
Date: Wed, 30 Apr 2025 09:51:03 +0800
From: Sung-Chi Li <lschyi@...omium.org>
To: Thomas Weißschuh <linux@...ssschuh.net>
Cc: Benson Leung <bleung@...omium.org>, Guenter Roeck <groeck@...omium.org>,
	Jean Delvare <jdelvare@...e.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Jonathan Corbet <corbet@....net>, chrome-platform@...ts.linux.dev,
	linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
	linux-doc@...r.kernel.org
Subject: Re: [PATCH 3/3] hwmon: (cros_ec) register fans into thermal
 framework cooling devices

On Tue, Apr 29, 2025 at 10:45:56PM +0200, Thomas Weißschuh wrote:
> On 2025-04-29 16:14:23+0800, Sung-Chi Li via B4 Relay wrote:
> > From: Sung-Chi Li <lschyi@...omium.org>
> > 
> > Register fans connected under EC as thermal cooling devices as well, so
> > these fans can then work with the thermal framework.
> > 
> > During the driver probing phase, we will also try to register each fan
> > as a thermal cooling device based on previous probe result (whether the
> > there are fans connected on that channel, and whether EC supports fan
> > control). The basic get max state, get current state, and set current
> > state methods are then implemented as well.
> 
> There is also HWMON_C_REGISTER_TZ, however it depends on OF.
> But this patch looks very generic, so maybe it makes sense to implement
> it in the hwmon core.
> 

Hi, the HWMON_C_REGISTER_TZ is for registering a thermal sensor, and here I
registered it as thermal cooling devices, so they are different. I followed
other hwmon drivers:

  - gpio-fan.c
  - aspeed-pwm-tacho.c
  - max6650.c
  - qnap-mcu-hwmon.c
  - ...

. These hwmon drivers also manually registered other cooling devices, and that
makes sense to me, so I think it is good to just register cooling devices rather
than make big changes to hwmon core.

> > Signed-off-by: Sung-Chi Li <lschyi@...omium.org>
> > ---
> >  Documentation/hwmon/cros_ec_hwmon.rst |  2 +
> >  drivers/hwmon/cros_ec_hwmon.c         | 72 +++++++++++++++++++++++++++++++++++
> >  2 files changed, 74 insertions(+)
> 
> <snip>