Message-Id: <D89LODODY167.1VG4P7K7X2BZO@gmail.com>
Date: Thu, 06 Mar 2025 19:16:50 -0500
From: "Kurt Borja" <kuurtb@...il.com>
To: "Armin Wolf" <W_Armin@....de>, Ilpo Järvinen
 <ilpo.jarvinen@...ux.intel.com>
Cc: "Hans de Goede" <hdegoede@...hat.com>,
 <platform-driver-x86@...r.kernel.org>, <Dell.Client.Kernel@...l.com>,
 <linux-kernel@...r.kernel.org>, "Guenter Roeck" <linux@...ck-us.net>, "Jean
 Delvare" <jdelvare@...e.com>, <linux-hwmon@...r.kernel.org>
Subject: Re: [PATCH v3 08/10] platform/x86: alienware-wmi-wmax: Add support
 for manual fan control

Hi Armin,

On Thu Mar 6, 2025 at 5:35 PM -05, Armin Wolf wrote:
> Am 06.03.25 um 01:56 schrieb Kurt Borja:
>
>> All models with the "AWCC" WMAX device support a way of manually
>> controlling fans.
>>
>> The PWM duty cycle of a fan can't be controlled directly. Instead the
>> AWCC interface let's us tune a PWM `boost` value, which has the
>> following empirically discovered, aproximate behavior over the PWM
>> value:
>>
>> 	pwm = pwm_base + (pwm_boost / 255) * (pwm_max - pwm_base)
>>
>> Where the pwm_base is the locked PWM value controlled by the FW and
>> pwm_boost is a value between 0 and 255.
>>
>> Expose this pwm_boost knob as a custom HWMON attribute.
>>
>> Cc: Guenter Roeck <linux@...ck-us.net>
>> Cc: Jean Delvare <jdelvare@...e.com>
>> Cc: linux-hwmon@...r.kernel.org
>> Signed-off-by: Kurt Borja <kuurtb@...il.com>
>> ---
>>   drivers/platform/x86/dell/alienware-wmi-wmax.c | 223 ++++++++++++++++++++++++-
>>   1 file changed, 220 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/platform/x86/dell/alienware-wmi-wmax.c b/drivers/platform/x86/dell/alienware-wmi-wmax.c
>> index 20cf3371ee3c0e1ea038b3ca517e831f3b30dc29..de4e8f177aadc9552b05cc732e41ee458b761143 100644
>> --- a/drivers/platform/x86/dell/alienware-wmi-wmax.c
>> +++ b/drivers/platform/x86/dell/alienware-wmi-wmax.c
>> @@ -13,8 +13,11 @@
>>   #include <linux/bits.h>
>>   #include <linux/dmi.h>
>>   #include <linux/hwmon.h>
>> +#include <linux/hwmon-sysfs.h>
>> +#include <linux/minmax.h>
>>   #include <linux/moduleparam.h>
>>   #include <linux/platform_profile.h>
>> +#include <linux/pm.h>
>>   #include <linux/units.h>
>>   #include <linux/wmi.h>
>>   #include "alienware-wmi.h"
>> @@ -179,10 +182,12 @@ enum AWCC_THERMAL_INFORMATION_OPERATIONS {
>>   	AWCC_OP_GET_FAN_MIN_RPM			= 0x08,
>>   	AWCC_OP_GET_FAN_MAX_RPM			= 0x09,
>>   	AWCC_OP_GET_CURRENT_PROFILE		= 0x0B,
>> +	AWCC_OP_GET_FAN_BOOST			= 0x0C,
>>   };
>>
>>   enum AWCC_THERMAL_CONTROL_OPERATIONS {
>>   	AWCC_OP_ACTIVATE_PROFILE		= 0x01,
>> +	AWCC_OP_SET_FAN_BOOST			= 0x02,
>>   };
>>
>>   enum AWCC_GAME_SHIFT_STATUS_OPERATIONS {
>> @@ -248,6 +253,7 @@ struct awcc_fan_data {
>>   	u32 total_temps;
>>   	u32 min_rpm;
>>   	u32 max_rpm;
>> +	u8 suspend_cache;
>>   	u8 id;
>>   };
>>
>> @@ -627,6 +633,17 @@ static inline int awcc_op_get_temperature(struct wmi_device *wdev, u8 temp_id, u
>>   		.arg3 = 0,
>>   	};
>>
>> +	return __awcc_wmi_command(wdev, AWCC_METHOD_THERMAL_INFORMATION, &args, out);
>> +}
>> +
>> +static inline int awcc_op_get_fan_boost(struct wmi_device *wdev, u8 fan_id, u32 *out)
>> +{
>> +	struct wmax_u32_args args = {
>> +		.operation = AWCC_OP_GET_FAN_BOOST,
>> +		.arg1 = fan_id,
>> +		.arg2 = 0,
>> +		.arg3 = 0,
>> +	};
>>
>>   	return __awcc_wmi_command(wdev, AWCC_METHOD_THERMAL_INFORMATION, &args, out);
>>   }
>> @@ -656,6 +673,19 @@ static inline int awcc_op_activate_profile(struct wmi_device *wdev, u8 profile)
>>   	return __awcc_wmi_command(wdev, AWCC_METHOD_THERMAL_CONTROL, &args, &out);
>>   }
>>
>> +static int awcc_op_set_fan_boost(struct wmi_device *wdev, u8 fan_id, u8 boost)
>> +{
>> +	struct wmax_u32_args args = {
>> +		.operation = AWCC_OP_SET_FAN_BOOST,
>> +		.arg1 = fan_id,
>> +		.arg2 = boost,
>> +		.arg3 = 0,
>> +	};
>> +	u32 out;
>> +
>> +	return __awcc_wmi_command(wdev, AWCC_METHOD_THERMAL_CONTROL, &args, &out);
>> +}
>> +
>>   static int awcc_profile_id_to_pprof(u32 id, enum platform_profile_option *profile)
>>   {
>>   	switch (id) {
>> @@ -717,6 +747,7 @@ static int awcc_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
>>   			   u32 attr, int channel, long *val)
>>   {
>>   	struct awcc_priv *priv = dev_get_drvdata(dev);
>> +	enum platform_profile_option profile;
>>   	struct awcc_fan_data *fan;
>>   	u32 state;
>>   	int ret;
>> @@ -765,6 +796,28 @@ static int awcc_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
>>   		fan = priv->fan_data[channel];
>>
>>   		switch (attr) {
>> +		case hwmon_pwm_enable:
>> +			ret = awcc_op_get_current_profile(priv->wdev, &state);
>> +			if (ret)
>> +				return ret;
>> +
>> +			ret = awcc_profile_id_to_pprof(state, &profile);
>> +			if (ret)
>> +				return ret;
>> +
>> +			switch (profile) {
>> +			case PLATFORM_PROFILE_PERFORMANCE:
>
> The hwmon sysfs docs say that 0 means that the fan is spinning at maximum speed. Does PLATFORM_PROFILE_PERFORMANCE
> guarantee that all fans are always spinning at maximum speed?

Yes PERFORMANCE is full-speed for all devices I know. Manual fan control
is completely disabled for that profile too.

In fact I'm thinking about adding a module parameter to suppress this
behavior. Not everyone may like that. That's outside the scope of these
series tho.

>
> If no then i suggest to drop support for 0.
>
>> +				*val = 0;
>> +				break;
>> +			case PLATFORM_PROFILE_CUSTOM:
>> +				*val = 1;
>> +				break;
>> +			default:
>> +				*val = 2;
>> +				break;
>> +			}
>> +
>> +			break;
>>   		case hwmon_pwm_auto_channels_temp:
>>   			bitmap_copy(val, fan->auto_channels_temp, BITS_PER_LONG);
>>   			break;
>> @@ -840,10 +893,48 @@ static int awcc_hwmon_read_string(struct device *dev, enum hwmon_sensor_types ty
>>   	return 0;
>>   }
>>
>> +
>> +static int awcc_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
>> +			    u32 attr, int channel, long val)
>> +{
>> +	struct awcc_priv *priv = dev_get_drvdata(dev);
>> +	int ret;
>> +
>> +	switch (type) {
>> +	case hwmon_pwm:
>> +		switch (attr) {
>> +		case hwmon_pwm_enable:
>> +			/*
>> +			 * We don't want to duplicate platform profile logic, so
>> +			 * we only allow enabling manual fan control
>> +			 */
>
> I do not think that having pwm1_enable brings any benefit, as the pwmX_boost attributes
> behave differently than pwmX attributes. I think it would be enough to document that
> pwmX_boost settings will only reliably work when the custom platform profile is selected.

Now I realise I completely forgot about the admin-guide documentation!
I'll include it in the next revision. Is this path ok?

	Documentation/admin-guide/laptops/alienware-wmi.rst

Or should I add driver specific ABI documentation? (or both ofc)

I don't want to name the file alienware-laptop because this driver is
compatible with Dell G-Series too.

>
>> +			if (val != 1)
>> +				return -EINVAL;
>> +
>> +			ret = awcc_op_activate_profile(priv->wdev, AWCC_SPECIAL_PROFILE_CUSTOM);
>> +			if (ret)
>> +				return ret;
>> +
>> +			if (priv->ppdev)
>> +				platform_profile_notify(priv->ppdev);
>> +			break;
>> +		default:
>> +			return -EOPNOTSUPP;
>> +		}
>> +
>> +		break;
>> +	default:
>> +		return -EOPNOTSUPP;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>>   static const struct hwmon_ops awcc_hwmon_ops = {
>>   	.is_visible = awcc_hwmon_is_visible,
>>   	.read = awcc_hwmon_read,
>>   	.read_string = awcc_hwmon_read_string,
>> +	.write = awcc_hwmon_write,
>>   };
>>
>>   static const struct hwmon_channel_info * const awcc_hwmon_info[] = {
>> @@ -864,7 +955,7 @@ static const struct hwmon_channel_info * const awcc_hwmon_info[] = {
>>   			   HWMON_F_LABEL | HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_MAX
>>   			   ),
>>   	HWMON_CHANNEL_INFO(pwm,
>> -			   HWMON_PWM_AUTO_CHANNELS_TEMP,
>> +			   HWMON_PWM_AUTO_CHANNELS_TEMP | HWMON_PWM_ENABLE,
>>   			   HWMON_PWM_AUTO_CHANNELS_TEMP,
>>   			   HWMON_PWM_AUTO_CHANNELS_TEMP,
>>   			   HWMON_PWM_AUTO_CHANNELS_TEMP,
>> @@ -879,6 +970,75 @@ static const struct hwmon_chip_info awcc_hwmon_chip_info = {
>>   	.info = awcc_hwmon_info,
>>   };
>>
>> +static ssize_t pwm_boost_show(struct device *dev, struct device_attribute *attr,
>> +			      char *buf)
>> +{
>> +	int ret, index = to_sensor_dev_attr(attr)->index;
>
> Please initialize "index" on a separate line, can remember the reverse xmas-tree order for variables.

Ack.

>
>> +	struct awcc_priv *priv = dev_get_drvdata(dev);
>> +	struct awcc_fan_data *fan = priv->fan_data[index];
>> +	u32 boost;
>> +
>> +	ret = awcc_op_get_fan_boost(priv->wdev, fan->id, &boost);
>> +	if (ret)
>> +		return ret;
>> +
>> +	return sysfs_emit(buf, "%u\n", boost);
>> +}
>> +
>> +static ssize_t pwm_boost_store(struct device *dev, struct device_attribute *attr,
>> +			       const char *buf, size_t count)
>> +{
>> +	int ret, index = to_sensor_dev_attr(attr)->index;
>> +	struct awcc_priv *priv = dev_get_drvdata(dev);
>> +	struct awcc_fan_data *fan = priv->fan_data[index];
>> +	unsigned long val;
>> +
>> +	ret = kstrtoul(buf, 0, &val);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = awcc_op_set_fan_boost(priv->wdev, fan->id, clamp_val(val, 0, 255));
>> +
>> +	return ret ? ret : count;
>> +}
>> +
>> +static SENSOR_DEVICE_ATTR_RW(pwm1_boost, pwm_boost, 0);
>> +static SENSOR_DEVICE_ATTR_RW(pwm2_boost, pwm_boost, 1);
>> +static SENSOR_DEVICE_ATTR_RW(pwm3_boost, pwm_boost, 2);
>> +static SENSOR_DEVICE_ATTR_RW(pwm4_boost, pwm_boost, 3);
>
> Since those attributes are working differently than the standard pwm attributes, i suggest to
> instead name them fanX_boost.

I went for pwm*_boost because we also export pwm*_auto_channels_temp,
but I'm ok with fan*_boost too.

>
>> +
>> +static umode_t pwm_boost_attr_visible(struct kobject *kobj, struct attribute *attr, int n)
>> +{
>> +	struct awcc_priv *priv = dev_get_drvdata(kobj_to_dev(kobj));
>> +
>> +	return n < priv->fan_count ? attr->mode : 0;
>> +}
>> +
>> +static bool pwm_boost_group_visible(struct kobject *kobj)
>> +{
>> +	return true;
>> +}
>> +
>> +DEFINE_SYSFS_GROUP_VISIBLE(pwm_boost);
>> +
>> +static struct attribute *fan_boost_attrs[] = {
>> +	&sensor_dev_attr_pwm1_boost.dev_attr.attr,
>> +	&sensor_dev_attr_pwm2_boost.dev_attr.attr,
>> +	&sensor_dev_attr_pwm3_boost.dev_attr.attr,
>> +	&sensor_dev_attr_pwm4_boost.dev_attr.attr,
>> +	NULL
>> +};
>> +
>> +static const struct attribute_group pwm_boost_group = {
>> +	.attrs = fan_boost_attrs,
>> +	.is_visible = SYSFS_GROUP_VISIBLE(pwm_boost),
>> +};
>> +
>> +static const struct attribute_group *awcc_hwmon_groups[] = {
>> +	&pwm_boost_group,
>> +	NULL
>> +};
>> +
>>   static int awcc_hwmon_temps_init(struct wmi_device *wdev)
>>   {
>>   	struct awcc_priv *priv = dev_get_drvdata(&wdev->dev);
>> @@ -1011,12 +1171,50 @@ static int awcc_hwmon_init(struct wmi_device *wdev)
>>   	if (ret)
>>   		return ret;
>>
>> -	priv->hwdev = devm_hwmon_device_register_with_info(&wdev->dev, "alienware_wmi", priv,
>> -							   &awcc_hwmon_chip_info, NULL);
>> +	priv->hwdev = devm_hwmon_device_register_with_info(&wdev->dev, "alienware_wmi",
>> +							   priv, &awcc_hwmon_chip_info,
>> +							   awcc_hwmon_groups);
>>
>>   	return PTR_ERR_OR_ZERO(priv->hwdev);
>>   }
>>
>> +static void awcc_hwmon_suspend(struct device *dev)
>> +{
>> +	struct awcc_priv *priv = dev_get_drvdata(dev);
>> +	struct awcc_fan_data *fan;
>> +	unsigned int i;
>> +	u32 boost;
>> +	int ret;
>> +
>> +	for (i = 0; i < priv->fan_count; i++) {
>> +		fan = priv->fan_data[i];
>> +
>> +		ret = awcc_thermal_information(priv->wdev, AWCC_OP_GET_FAN_BOOST,
>> +					       fan->id, &boost);
>> +		if (ret)
>> +			fan->suspend_cache = 0;
>
> Please at least log a warning here that the fan boost value can not be restored properly.

Ack.

Is not propagating errors a good approach here? My idea was to try to
turn off fans no matter what.

>
>> +		else
>> +			fan->suspend_cache = clamp_val(boost, 0, 255);
>> +
>> +		awcc_op_set_fan_boost(priv->wdev, fan->id, 0);
>> +	}
>> +}
>> +
>> +static void awcc_hwmon_resume(struct device *dev)
>> +{
>> +
>> +	struct awcc_priv *priv = dev_get_drvdata(dev);
>> +	struct awcc_fan_data *fan;
>> +	unsigned int i;
>> +
>> +	for (i = 0; i < priv->fan_count; i++) {
>> +		fan = priv->fan_data[i];
>> +
>> +		if (fan->suspend_cache)
>
> How does the driver restore fan boost settings with a value of 0?

We set to 0 when suspending so I don't think it's necessary to restore
to 0 again when resuming.

>
> Thanks,
> Armin Wolf
>
>> +			awcc_op_set_fan_boost(priv->wdev, fan->id, fan->suspend_cache);
>> +	}
>> +}
>> +
>>   /*
>>    * Thermal Profile control
>>    *  - Provides thermal profile control through the Platform Profile API
>> @@ -1233,6 +1431,24 @@ static int wmax_wmi_probe(struct wmi_device *wdev, const void *context)
>>   	return ret;
>>   }
>>
>> +static int wmax_wmi_suspend(struct device *dev)
>> +{
>> +	if (awcc->hwmon)
>> +		awcc_hwmon_suspend(dev);
>> +
>> +	return 0;
>> +}
>> +
>> +static int wmax_wmi_resume(struct device *dev)
>> +{
>> +	if (awcc->hwmon)
>> +		awcc_hwmon_resume(dev);
>> +
>> +	return 0;
>> +}
>> +
>> +DEFINE_SIMPLE_DEV_PM_OPS(wmax_wmi_pm_ops, wmax_wmi_suspend, wmax_wmi_resume);
>> +
>>   static const struct wmi_device_id alienware_wmax_device_id_table[] = {
>>   	{ WMAX_CONTROL_GUID, NULL },
>>   	{ },
>> @@ -1243,6 +1459,7 @@ static struct wmi_driver alienware_wmax_wmi_driver = {
>>   	.driver = {
>>   		.name = "alienware-wmi-wmax",
>>   		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
>> +		.pm = pm_sleep_ptr(&wmax_wmi_pm_ops),
>>   	},
>>   	.id_table = alienware_wmax_device_id_table,
>>   	.probe = wmax_wmi_probe,
>>


-- 
 ~ Kurt

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