Re: [PATCH 7/7] platform/x86: asus-wmi: show the effective duty for enabled curves

[Ilpo Järvinen]

On Sun, 1 Nov 2026, Bartu Alev wrote:

> When a custom fan curve is enabled, the embedded controller executes
> each point at max(written_duty, floor_duty).  However,
> pwmY_auto_pointZ_pwm reports only the stored value, diverging from
> the duty applied by hardware.
> 
> Return max(stored, floor) from pwmY_auto_pointZ_pwm when the curve is
> enabled and floor data is valid.  When disabled, continue returning
> the stored value.
> 
> Because the controller operates in integer percentages while sysfs
> uses PWM units (0-255), the reported value is an upper bound of the
> applied duty.  Consequently, reading an enabled curve is not
> read/modify/write safe: writing back a read value commits the
> firmware floor into the stored curve.
> 
> Trigger sysfs notifications on pwmY_auto_pointZ_pwm on enable and
> disable transitions, as well as floor refreshes, so pollers detect
> changes in effective duty.
> 
> Signed-off-by: Bartu Alev <bartualev@xxxxxxxxx>
> ---
>  Documentation/ABI/testing/sysfs-platform-asus-wmi | 14 +++++++++++
>  drivers/platform/x86/asus-wmi.c                   | 30 +++++++++++++++++++----
>  2 files changed, 39 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-platform-asus-wmi b/Documentation/ABI/testing/sysfs-platform-asus-wmi
> index 24931cc97ca86..36b633a5dfc49 100644
> --- a/Documentation/ABI/testing/sysfs-platform-asus-wmi
> +++ b/Documentation/ABI/testing/sysfs-platform-asus-wmi
> @@ -281,6 +281,20 @@ Description:
>  		(0-255); the driver scales the duty to the percentage the
>  		firmware expects when the curve is enabled.
>  
> +		While the curve is enabled, _pwm reports the effective duty,
> +		which is the higher of the stored duty and the firmware floor
> +		of the point (pwmY_auto_pointZ_floor_pwm).  A disabled curve
> +		reports the stored duty.  The controller works in whole
> +		percent, so the reported value is an upper bound: the applied
> +		duty can be up to 2.5 pwm units lower.
> +
> +		Reading while the curve is enabled is therefore not
> +		read-modify-write safe: a curve editor that reads the points
> +		and writes them back stores the effective duty as the new
> +		curve, and the duty the user originally wrote is lost.  Read
> +		the curve while it is disabled, or write back the values that
> +		were written rather than the ones that were read.
> +
>  		The embedded controller binds point Z (Z = 1..8) to the
>  		temperature decade [30 + 10 * (Z - 1), 39 + 10 * (Z - 1)]
>  		degrees Celsius and silently clamps the threshold into that
> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
> index 74476904cb99c..bae5a528ac5d8 100644
> --- a/drivers/platform/x86/asus-wmi.c
> +++ b/drivers/platform/x86/asus-wmi.c
> @@ -324,7 +324,7 @@ struct asus_wmi {
>  	bool gpu_fan_curve_available;
>  	bool mid_fan_curve_available;
>  	struct fan_curve_data custom_fan_curves[3];
> -	/* protects custom_fan_curves[].floors */
> +	/* protects custom_fan_curves[].floors and .floors_valid */
>  	struct mutex fan_curve_lock;
>  	struct device *fan_curve_hwmon;
>  
> @@ -3754,7 +3754,7 @@ static int fan_curve_load_floors(struct asus_wmi *asus, u32 fan_dev)
>  	return 0;
>  }
>  
> -static void fan_curve_notify_floors(struct asus_wmi *asus)
> +static void fan_curve_notify(struct asus_wmi *asus)
>  {
>  	struct device *hwmon = asus->fan_curve_hwmon;
>  	bool valid[ARRAY_SIZE(asus->custom_fan_curves)];
> @@ -3778,6 +3778,10 @@ static void fan_curve_notify_floors(struct asus_wmi *asus)
>  				 "pwm%d_auto_point%d_floor_pwm",
>  				 fan + 1, point + 1);
>  			sysfs_notify(&hwmon->kobj, NULL, name);
> +			snprintf(name, sizeof(name),

scnprintf()

> +				 "pwm%d_auto_point%d_pwm",
> +				 fan + 1, point + 1);
> +			sysfs_notify(&hwmon->kobj, NULL, name);
>  		}
>  	}
>  }
> @@ -3797,7 +3801,7 @@ static void fan_curve_refresh_floors(struct asus_wmi *asus)
>  	if (asus->mid_fan_curve_available)
>  		fan_curve_load_floors(asus, ASUS_WMI_DEVID_MID_FAN_CURVE);
>  
> -	fan_curve_notify_floors(asus);
> +	fan_curve_notify(asus);
>  }
>  
>  /* Check if the capability exists, populate its defaults and read its floor table */
> @@ -3855,15 +3859,28 @@ static ssize_t fan_curve_show(struct device *dev,
>  	struct asus_wmi *asus = dev_get_drvdata(dev);
>  	struct fan_curve_data *data;
>  	int value, pwm, index;
> +	bool enabled;
>  
>  	data = fan_curve_attr_2_select(asus, attr);
>  	pwm = dev_attr->nr & FAN_CURVE_PWM_MASK;
>  	index = dev_attr->index;
>  
> -	if (pwm)
> +	if (pwm) {
> +		enabled = data->enabled;
>  		value = data->percents[index];
> -	else
> +
> +		/*
> +		 * The EC runs the point at the higher of the curve and the
> +		 * firmware floor, so report the duty it applies.  Only the
> +		 * floor table is protected by fan_curve_lock; enabled and
> +		 * percents are written without it, so this is a snapshot.
> +		 */
> +		guard(mutex)(&asus->fan_curve_lock);
> +		if (enabled && data->floors_valid)
> +			value = max(value, (int)data->floors[index]);
> +	} else {
>  		value = data->temps[index];
> +	}
>  
>  	return sysfs_emit(buf, "%d\n", value);
>  }
> @@ -4059,6 +4076,9 @@ static ssize_t fan_curve_enable_store(struct device *dev,
>  			fan_curve_refresh_floors(asus);
>  		}
>  	}
> +
> +	fan_curve_notify(asus);
> +
>  	return count;
>  }
>  
> 
> 

-- 
 i.