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

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Message-ID: <aFO82_5riDyC0FMs@google.com>
Date: Thu, 19 Jun 2025 15:31:39 +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 v3 3/3] hwmon: (cros_ec) register fans into thermal
 framework cooling devices

On Mon, May 12, 2025 at 09:35:47AM +0200, Thomas Weißschuh wrote:
> On 2025-05-12 15:11:57+0800, Sung-Chi Li via B4 Relay wrote:
> > +	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.
> 

After rethinking  about the logic, I think I should try and register all fans
with best effort, so I should not return immediately; instead, I will log an
warning log, and continue with the next fan.

> > +
> > +		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.
> 

Thank you, will use IS_ERR for checking and %pe to print error.

> > +			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
> > 
> >