Message-ID: <2e942b2e-e697-4298-8328-2dd773a8cb4a@gmx.de>
Date: Thu, 2 Oct 2025 21:23:44 +0200
From: Armin Wolf <W_Armin@....de>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: jlee@...e.com, basak.sb2006@...il.com, rayanmargham4@...il.com,
 kuurtb@...il.com, platform-driver-x86@...r.kernel.org,
 LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/4] platform/x86: acer-wmi: Add fan control support

Am 24.09.25 um 12:52 schrieb Ilpo Järvinen:

> On Tue, 23 Sep 2025, Armin Wolf wrote:
>
>> Add support for controlling the fan speed using the
>> SetGamingFanSpeed() and GetGamingFanSpeed() WMI methods.
>>
>> This feature is only enabled if the machine has ACER_CAP_PWM enabled
>> and depend on ACER_CAP_HWMON for detecting the number of available
>> fans.
>>
>> Reviewed-by: Kurt Borja <kuurtb@...il.com>
>> Signed-off-by: Armin Wolf <W_Armin@....de>
>> ---
>>   drivers/platform/x86/acer-wmi.c | 221 +++++++++++++++++++++++++++++++-
>>   1 file changed, 219 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/platform/x86/acer-wmi.c b/drivers/platform/x86/acer-wmi.c
>> index a41555ee8589..345b6e24ae31 100644
>> --- a/drivers/platform/x86/acer-wmi.c
>> +++ b/drivers/platform/x86/acer-wmi.c
>> @@ -12,10 +12,12 @@
>>   #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>>   
>>   #include <linux/kernel.h>
>> +#include <linux/minmax.h>
>>   #include <linux/module.h>
>>   #include <linux/init.h>
>>   #include <linux/types.h>
>>   #include <linux/dmi.h>
>> +#include <linux/fixp-arith.h>
>>   #include <linux/backlight.h>
>>   #include <linux/leds.h>
>>   #include <linux/platform_device.h>
>> @@ -69,11 +71,16 @@ MODULE_LICENSE("GPL");
>>   #define ACER_WMID_GET_GAMING_LED_METHODID 4
>>   #define ACER_WMID_GET_GAMING_SYS_INFO_METHODID 5
>>   #define ACER_WMID_SET_GAMING_FAN_BEHAVIOR_METHODID 14
>> +#define ACER_WMID_GET_GAMING_FAN_BEHAVIOR_METHODID 15
>> +#define ACER_WMID_SET_GAMING_FAN_SPEED_METHODID 16
>> +#define ACER_WMID_GET_GAMING_FAN_SPEED_METHODID 17
>>   #define ACER_WMID_SET_GAMING_MISC_SETTING_METHODID 22
>>   #define ACER_WMID_GET_GAMING_MISC_SETTING_METHODID 23
>>   
>> +#define ACER_GAMING_FAN_BEHAVIOR_STATUS_MASK GENMASK_ULL(7, 0)
>>   #define ACER_GAMING_FAN_BEHAVIOR_ID_MASK GENMASK_ULL(15, 0)
>>   #define ACER_GAMING_FAN_BEHAVIOR_SET_MODE_MASK GENMASK_ULL(23, 16)
>> +#define ACER_GAMING_FAN_BEHAVIOR_GET_MODE_MASK GENMASK_ULL(23, 8)
>>   
>>   #define ACER_GAMING_FAN_BEHAVIOR_CPU BIT(0)
>>   #define ACER_GAMING_FAN_BEHAVIOR_GPU BIT(3)
>> @@ -81,6 +88,10 @@ MODULE_LICENSE("GPL");
>>   #define ACER_GAMING_FAN_BEHAVIOR_CPU_MODE_MASK GENMASK(1, 0)
>>   #define ACER_GAMING_FAN_BEHAVIOR_GPU_MODE_MASK GENMASK(7, 6)
>>   
>> +#define ACER_GAMING_FAN_SPEED_STATUS_MASK GENMASK_ULL(7, 0)
>> +#define ACER_GAMING_FAN_SPEED_ID_MASK GENMASK_ULL(7, 0)
>> +#define ACER_GAMING_FAN_SPEED_VALUE_MASK GENMASK_ULL(15, 8)
>> +
>>   #define ACER_GAMING_MISC_SETTING_STATUS_MASK GENMASK_ULL(7, 0)
>>   #define ACER_GAMING_MISC_SETTING_INDEX_MASK GENMASK_ULL(7, 0)
>>   #define ACER_GAMING_MISC_SETTING_VALUE_MASK GENMASK_ULL(15, 8)
>> @@ -130,6 +141,11 @@ enum acer_wmi_predator_v4_sensor_id {
>>   	ACER_WMID_SENSOR_GPU_TEMPERATURE	= 0x0A,
>>   };
>>   
>> +enum acer_wmi_gaming_fan_id {
>> +	ACER_WMID_CPU_FAN	= 0x01,
>> +	ACER_WMID_GPU_FAN	= 0x04,
>> +};
> In patch 1 you added these:
>
> +#define ACER_GAMING_FAN_BEHAVIOR_ID_MASK GENMASK_ULL(15, 0)
> ...
> +#define ACER_GAMING_FAN_BEHAVIOR_CPU BIT(0)
> +#define ACER_GAMING_FAN_BEHAVIOR_GPU BIT(3)
>
> Are these numbers related (you even called the field "ID mask")? Could we
> do with less defines for the same thing if they're related?

I honestly don't know if those IDs are related. I would like to play it safe
and keep them separate for now.

>>   enum acer_wmi_gaming_fan_mode {
>>   	ACER_WMID_FAN_MODE_AUTO		= 0x01,
>>   	ACER_WMID_FAN_MODE_TURBO	= 0x02,
>> @@ -292,6 +308,7 @@ struct hotkey_function_type_aa {
>>   #define ACER_CAP_TURBO_FAN		BIT(9)
>>   #define ACER_CAP_PLATFORM_PROFILE	BIT(10)
>>   #define ACER_CAP_HWMON			BIT(11)
>> +#define ACER_CAP_PWM			BIT(12)
>>   
>>   /*
>>    * Interface type flags
>> @@ -386,6 +403,7 @@ struct quirk_entry {
>>   	u8 cpu_fans;
>>   	u8 gpu_fans;
>>   	u8 predator_v4;
>> +	u8 pwm;
>>   };
>>   
>>   static struct quirk_entry *quirks;
>> @@ -405,6 +423,9 @@ static void __init set_quirks(void)
>>   	if (quirks->predator_v4)
>>   		interface->capability |= ACER_CAP_PLATFORM_PROFILE |
>>   					 ACER_CAP_HWMON;
>> +
>> +	if (quirks->pwm)
>> +		interface->capability |= ACER_CAP_PWM;
>>   }
>>   
>>   static int __init dmi_matched(const struct dmi_system_id *dmi)
>> @@ -1651,6 +1672,27 @@ static int WMID_gaming_set_fan_behavior(u16 fan_bitmap, u8 mode_bitmap)
>>   	return 0;
>>   }
>>   
>> +static int WMID_gaming_get_fan_behavior(u16 fan_bitmap, u8 *mode_bitmap)
>> +{
>> +	acpi_status status;
>> +	u32 input = 0;
>> +	u64 result;
>> +
>> +	input |= FIELD_PREP(ACER_GAMING_FAN_BEHAVIOR_ID_MASK, fan_bitmap);
>> +	status = WMI_gaming_execute_u32_u64(ACER_WMID_GET_GAMING_FAN_BEHAVIOR_METHODID, input,
>> +					    &result);
>> +	if (ACPI_FAILURE(status))
>> +		return -EIO;
>> +
>> +	/* The return status must be zero for the operation to have succeeded */
>> +	if (FIELD_GET(ACER_GAMING_FAN_BEHAVIOR_STATUS_MASK, result))
>> +		return -EIO;
>> +
>> +	*mode_bitmap = FIELD_GET(ACER_GAMING_FAN_BEHAVIOR_GET_MODE_MASK, result);
>> +
>> +	return 0;
>> +}
>> +
>>   static void WMID_gaming_set_fan_mode(u8 fan_mode)
>>   {
>>   	u16 mode_bitmap = 0;
>> @@ -1669,6 +1711,55 @@ static void WMID_gaming_set_fan_mode(u8 fan_mode)
>>   	WMID_gaming_set_fan_behavior(fan_bitmap, mode_bitmap);
>>   }
>>   
>> +static int WMID_gaming_set_gaming_fan_speed(u8 fan, u8 speed)
>> +{
>> +	acpi_status status;
>> +	u64 input = 0;
>> +	u64 result;
>> +
>> +	if (speed > 100)
>> +		return -EINVAL;
>> +
>> +	input |= FIELD_PREP(ACER_GAMING_FAN_SPEED_ID_MASK, fan);
>> +	input |= FIELD_PREP(ACER_GAMING_FAN_SPEED_VALUE_MASK, speed);
>> +
>> +	status = WMI_gaming_execute_u64(ACER_WMID_SET_GAMING_FAN_SPEED_METHODID, input, &result);
>> +	if (ACPI_FAILURE(status))
>> +		return -EIO;
>> +
>> +	switch (FIELD_GET(ACER_GAMING_FAN_SPEED_STATUS_MASK, result)) {
>> +	case 0x00:
>> +		return 0;
>> +	case 0x01:
>> +		return -ENODEV;
>> +	case 0x02:
>> +		return -EINVAL;
>> +	default:
>> +		return -ENXIO;
>> +	}
>> +}
>> +
>> +static int WMID_gaming_get_gaming_fan_speed(u8 fan, u8 *speed)
>> +{
>> +	acpi_status status;
>> +	u32 input = 0;
>> +	u64 result;
>> +
>> +	input |= FIELD_PREP(ACER_GAMING_FAN_SPEED_ID_MASK, fan);
>> +
>> +	status = WMI_gaming_execute_u32_u64(ACER_WMID_GET_GAMING_FAN_SPEED_METHODID, input,
>> +					    &result);
>> +	if (ACPI_FAILURE(status))
>> +		return -EIO;
>> +
>> +	if (FIELD_GET(ACER_GAMING_FAN_SPEED_STATUS_MASK, result))
>> +		return -ENODEV;
>> +
>> +	*speed = FIELD_GET(ACER_GAMING_FAN_SPEED_VALUE_MASK, result);
>> +
>> +	return 0;
>> +}
>> +
>>   static int WMID_gaming_set_misc_setting(enum acer_wmi_gaming_misc_setting setting, u8 value)
>>   {
>>   	acpi_status status;
>> @@ -2840,6 +2931,16 @@ static const enum acer_wmi_predator_v4_sensor_id acer_wmi_fan_channel_to_sensor_
>>   	[1] = ACER_WMID_SENSOR_GPU_FAN_SPEED,
>>   };
>>   
>> +static const enum acer_wmi_gaming_fan_id acer_wmi_fan_channel_to_fan_id[] = {
>> +	[0] = ACER_WMID_CPU_FAN,
>> +	[1] = ACER_WMID_GPU_FAN,
>> +};
>> +
>> +static const u16 acer_wmi_fan_channel_to_fan_bitmap[] = {
>> +	[0] = ACER_GAMING_FAN_BEHAVIOR_CPU,
>> +	[1] = ACER_GAMING_FAN_BEHAVIOR_GPU,
>> +};
>> +
>>   static umode_t acer_wmi_hwmon_is_visible(const void *data,
>>   					 enum hwmon_sensor_types type, u32 attr,
>>   					 int channel)
>> @@ -2851,6 +2952,11 @@ static umode_t acer_wmi_hwmon_is_visible(const void *data,
>>   	case hwmon_temp:
>>   		sensor_id = acer_wmi_temp_channel_to_sensor_id[channel];
>>   		break;
>> +	case hwmon_pwm:
>> +		if (!has_cap(ACER_CAP_PWM))
>> +			return 0;
>> +
>> +		fallthrough;
>>   	case hwmon_fan:
>>   		sensor_id = acer_wmi_fan_channel_to_sensor_id[channel];
>>   		break;
>> @@ -2858,8 +2964,12 @@ static umode_t acer_wmi_hwmon_is_visible(const void *data,
>>   		return 0;
>>   	}
>>   
>> -	if (*supported_sensors & BIT(sensor_id - 1))
>> +	if (*supported_sensors & BIT(sensor_id - 1)) {
>> +		if (type == hwmon_pwm)
>> +			return 0644;
>> +
>>   		return 0444;
>> +	}
>>   
>>   	return 0;
>>   }
>> @@ -2868,8 +2978,10 @@ static int acer_wmi_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
>>   			       u32 attr, int channel, long *val)
>>   {
>>   	u64 command = ACER_WMID_CMD_GET_PREDATOR_V4_SENSOR_READING;
>> +	u8 fan, speed, mode_bitmap;
>> +	u16 fan_bitmap;
>> +	int mode, ret;
>>   	u64 result;
>> -	int ret;
>>   
>>   	switch (type) {
>>   	case hwmon_temp:
>> @@ -2893,6 +3005,106 @@ static int acer_wmi_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
>>   
>>   		*val = FIELD_GET(ACER_PREDATOR_V4_SENSOR_READING_BIT_MASK, result);
>>   		return 0;
>> +	case hwmon_pwm:
>> +		switch (attr) {
>> +		case hwmon_pwm_input:
>> +			fan = acer_wmi_fan_channel_to_fan_id[channel];
>> +			ret = WMID_gaming_get_gaming_fan_speed(fan, &speed);
>> +			if (ret < 0)
>> +				return ret;
>> +
>> +			*val = fixp_linear_interpolate(0, 0, 100, U8_MAX, speed);
>> +			return 0;
>> +		case hwmon_pwm_enable:
>> +			fan_bitmap = acer_wmi_fan_channel_to_fan_bitmap[channel];
>> +			ret = WMID_gaming_get_fan_behavior(fan_bitmap, &mode_bitmap);
>> +			if (ret < 0)
>> +				return ret;
>> +
>> +			switch (channel) {
>> +			case 0:
>> +				mode = FIELD_GET(ACER_GAMING_FAN_BEHAVIOR_CPU_MODE_MASK,
>> +						 mode_bitmap);
>> +				break;
>> +			case 1:
>> +				mode = FIELD_GET(ACER_GAMING_FAN_BEHAVIOR_GPU_MODE_MASK,
>> +						 mode_bitmap);
>> +				break;
>> +			default:
>> +				return -EINVAL;
>> +			}
> You've managed to create an internal API that resembles the WMI method
> input by working in terms of fan_bitmap and mode_bitmap which makes things
> complicated as then you have to build logic on top of it to do all the
> mapping in the caller...
>
> I suggest changing this so you make WMID_gaming_get_fan_behavior() to
> input ACER_GAMING_FAN_BEHAVIOR_CPU / GPU (or ACER_WMID_CPU_FAN / GPU_FAN
> depending on the question I asked above) and perform the output mapping
> within that function. I think it would be much cleaner.
>
> I didn't exactly like the internal API in patch 1 either and I'd prefer
> the field GENMASK()s to directly point to the correct bits instead of the
> nested FIELD_GET/PREP()s.

Ok, will do.

>> +			switch (mode) {
>> +			case ACER_WMID_FAN_MODE_AUTO:
>> +				*val = 2;
>> +				return 0;
>> +			case ACER_WMID_FAN_MODE_TURBO:
>> +				*val = 0;
>> +				return 0;
>> +			case ACER_WMID_FAN_MODE_CUSTOM:
>> +				*val = 1;
>> +				return 0;
>> +			default:
>> +				return -ENXIO;
>> +			}
>> +		default:
>> +			return -EOPNOTSUPP;
>> +		}
>> +	default:
>> +		return -EOPNOTSUPP;
>> +	}
>> +}
>> +
>> +static int acer_wmi_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
>> +				u32 attr, int channel, long val)
>> +{
>> +	u8 fan, speed, mode_bitmap;
>> +	u16 fan_bitmap;
>> +	int mode;
>> +
>> +	switch (type) {
>> +	case hwmon_pwm:
>> +		switch (attr) {
>> +		case hwmon_pwm_input:
>> +			fan = acer_wmi_fan_channel_to_fan_id[channel];
>> +			speed = fixp_linear_interpolate(0, 0, U8_MAX, 100,
>> +							clamp_val(val, 0, U8_MAX));
>> +
>> +			return WMID_gaming_set_gaming_fan_speed(fan, speed);
>> +		case hwmon_pwm_enable:
>> +			fan_bitmap = acer_wmi_fan_channel_to_fan_bitmap[channel];
>> +
>> +			switch (val) {
>> +			case 0:
>> +				mode = ACER_WMID_FAN_MODE_TURBO;
>> +				break;
>> +			case 1:
>> +				mode = ACER_WMID_FAN_MODE_CUSTOM;
>> +				break;
>> +			case 2:
>> +				mode = ACER_WMID_FAN_MODE_AUTO;
>> +				break;
>> +			default:
>> +				return -EINVAL;
>> +			}
>> +
>> +			switch (channel) {
>> +			case 0:
>> +				mode_bitmap = FIELD_PREP(ACER_GAMING_FAN_BEHAVIOR_CPU_MODE_MASK,
>> +							 mode);
>> +				break;
>> +			case 1:
>> +				mode_bitmap = FIELD_PREP(ACER_GAMING_FAN_BEHAVIOR_GPU_MODE_MASK,
>> +							 mode);
>> +				break;
>> +			default:
>> +				return -EINVAL;
>> +			}
> These too look they could be mapped inside WMID_gaming_set_fan_behavior().

I don't think so, as the function also needs to handle the setting of multiple fans
at once.

Thanks,
Armin Wolf

>> +
>> +			return WMID_gaming_set_fan_behavior(fan_bitmap, mode_bitmap);
>> +		default:
>> +			return -EOPNOTSUPP;
>> +		}
>>   	default:
>>   		return -EOPNOTSUPP;
>>   	}
>> @@ -2908,11 +3120,16 @@ static const struct hwmon_channel_info *const acer_wmi_hwmon_info[] = {
>>   			   HWMON_F_INPUT,
>>   			   HWMON_F_INPUT
>>   			   ),
>> +	HWMON_CHANNEL_INFO(pwm,
>> +			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
>> +			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE
>> +			   ),
>>   	NULL
>>   };
>>   
>>   static const struct hwmon_ops acer_wmi_hwmon_ops = {
>>   	.read = acer_wmi_hwmon_read,
>> +	.write = acer_wmi_hwmon_write,
>>   	.is_visible = acer_wmi_hwmon_is_visible,
>>   };
>>   
>>

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