linux-kernel - Re: [PATCH v3 3/3] hwmon: (cros_ec) register fans into thermal framework cooling devices

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Message-ID: <7309c804-19e3-4715-b8c9-efa31c8ea9e1@t-8ch.de>
Date: Mon, 12 May 2025 09:35:47 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: lschyi@...omium.org
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, Sung-Chi Li <lschyi@...gle.com>
Subject: Re: [PATCH v3 3/3] hwmon: (cros_ec) register fans into thermal
 framework cooling devices

On 2025-05-12 15:11:57+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.
> 
> Signed-off-by: Sung-Chi Li <lschyi@...omium.org>
> ---
>  Documentation/hwmon/cros_ec_hwmon.rst |  2 +
>  drivers/hwmon/cros_ec_hwmon.c         | 78 +++++++++++++++++++++++++++++++++++
>  2 files changed, 80 insertions(+)

<snip>

> +static void cros_ec_hwmon_register_fan_cooling_devices(struct device *dev,
> +						       struct cros_ec_hwmon_priv *priv)
> +{
> +	struct thermal_cooling_device *cdev;
> +	struct cros_ec_hwmon_cooling_priv *cpriv;
> +	size_t i;
> +	char *type;

Ordering.

> +
> +	if (!IS_ENABLED(CONFIG_THERMAL))
> +		return;
> +
> +	if (!priv->fan_control_supported)
> +		return;
> +
> +	for (i = 0; i < EC_FAN_SPEED_ENTRIES; i++) {
> +		if (!(priv->usable_fans & BIT(i)))
> +			continue;
> +
> +		cpriv = devm_kzalloc(dev, sizeof(*cpriv), GFP_KERNEL);
> +		if (!cpriv)
> +			return;

The failures are swallowed silently. They should be propagated.

> +
> +		type = devm_kasprintf(dev, GFP_KERNEL, "%s-fan%zu", dev_name(dev), i);
> +		if (!type)
> +			return;
> +
> +		cpriv->hwmon_priv = priv;
> +		cpriv->index = i;
> +		cdev = devm_thermal_of_cooling_device_register(dev, NULL, type, cpriv,
> +							       &cros_ec_thermal_cooling_ops);
> +		if (!cdev)

..._cooling_device_register() returns an error pointer on failure, not NULL.

> +			return;
> +	}
> +}
> +
>  static int cros_ec_hwmon_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -412,6 +489,7 @@ static int cros_ec_hwmon_probe(struct platform_device *pdev)
>  	cros_ec_hwmon_probe_temp_sensors(dev, priv, thermal_version);
>  	cros_ec_hwmon_probe_fans(priv);
>  	priv->fan_control_supported = cros_ec_hwmon_probe_fan_control_supported(priv->cros_ec);
> +	cros_ec_hwmon_register_fan_cooling_devices(dev, priv);
>  
>  	hwmon_dev = devm_hwmon_device_register_with_info(dev, "cros_ec", priv,
>  							 &cros_ec_hwmon_chip_info, NULL);
> 
> -- 
> 2.49.0.1015.ga840276032-goog
> 
>