Re: [PATCH v2 2/2] platform/x86: asus-armoury: expose requires_fan_curve via sysfs

[Mario Limonciello <superm1@kernel.org>]

On 5/13/26 10:47 AM, Ahmed Yaseen wrote:
> Expose the per-model requires_fan_curve flag as a read-only sysfs
> attribute so userspace tools (asusctl, rogcc) can discover whether
> the system requires an active custom fan curve for PPT changes to
> take effect, and warn the user before issuing such writes.
> 
> The attribute appears at:
>    /sys/class/firmware-attributes/asus-armoury/attributes/requires_fan_curve
> 
> Document the attribute in
> Documentation/ABI/testing/sysfs-class-firmware-attributes.
> 
> Signed-off-by: Ahmed Yaseen <yaseen@ghoul.dev>
> ---
>   .../testing/sysfs-class-firmware-attributes   | 25 +++++++++++++++++++
>   drivers/platform/x86/asus-armoury.c           | 15 +++++++++++
>   2 files changed, 40 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-firmware-attributes b/Documentation/ABI/testing/sysfs-class-firmware-attributes
> index 2713efa509b4..12700a077f43 100644
> --- a/Documentation/ABI/testing/sysfs-class-firmware-attributes
> +++ b/Documentation/ABI/testing/sysfs-class-firmware-attributes
> @@ -492,3 +492,28 @@ Description:
>   		log entry size identifies audit log size for the current BIOS version.
>   		The current size is 16 bytes but it can be up to 128 bytes long in future BIOS
>   		versions.
> +
> +What:		/sys/class/firmware-attributes/asus-armoury/attributes/requires_fan_curve
> +Date:		May 2026
> +KernelVersion:	7.1

Right now we're submitting content for 7.2 or later, so this should be 
updated.

> +Contact:	platform-driver-x86@vger.kernel.org
> +Description:
> +		A read-only attribute that reads 1 on ASUS ROG models where the
> +		BIOS requires a custom fan curve to be active before Package
> +		Power Tracking (PPT) writes take effect. On affected models, the
> +		BIOS silently ignores writes to ppt_pl1_spl, ppt_pl2_sppt,
> +		ppt_pl3_fppt, ppt_apu_sppt and ppt_platform_sppt unless a custom
> +		fan curve has been written via the asus_custom_fan_curve hwmon
> +		device.
> +
> +		The kernel rejects PPT writes with -EBUSY on these models when
> +		no fan curve is active. Userspace tools can read this attribute
> +		to surface a clear prerequisite to the user instead of letting
> +		the write appear to succeed at the firmware-attribute layer
> +		while the BIOS discards it.
> +
> +			==	==============================================
> +			0	No fan curve prerequisite for PPT writes.
> +			1	A custom fan curve must be active; PPT writes
> +				return -EBUSY otherwise.
> +			==	==============================================
> diff --git a/drivers/platform/x86/asus-armoury.c b/drivers/platform/x86/asus-armoury.c
> index 9b1c41a25b38..9b483d7e9855 100644
> --- a/drivers/platform/x86/asus-armoury.c
> +++ b/drivers/platform/x86/asus-armoury.c
> @@ -127,6 +127,13 @@ static ssize_t pending_reboot_show(struct kobject *kobj, struct kobj_attribute *
>   
>   static struct kobj_attribute pending_reboot = __ATTR_RO(pending_reboot);
>   
> +static ssize_t requires_fan_curve_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
> +{
> +	return sysfs_emit(buf, "%d\n", asus_armoury.requires_fan_curve);
> +}
> +
> +static struct kobj_attribute requires_fan_curve = __ATTR_RO(requires_fan_curve);
> +
>   static bool asus_bios_requires_reboot(struct kobj_attribute *attr)
>   {
>   	return !strcmp(attr->attr.name, "gpu_mux_mode") ||
> @@ -914,6 +921,12 @@ static int asus_fw_attr_add(void)
>   		goto err_destroy_kset;
>   	}
>   
> +	err = sysfs_create_file(&asus_armoury.fw_attr_kset->kobj, &requires_fan_curve.attr);
> +	if (err) {
> +		pr_err("Failed to create requires_fan_curve attribute\n");
> +		goto err_destroy_kset;
> +	}
> +
>   	asus_armoury.mini_led_dev_id = 0;
>   	if (armoury_has_devstate(ASUS_WMI_DEVID_MINI_LED_MODE))
>   		asus_armoury.mini_led_dev_id = ASUS_WMI_DEVID_MINI_LED_MODE;
> @@ -987,6 +1000,7 @@ static int asus_fw_attr_add(void)
>   	if (asus_armoury.mini_led_dev_id)
>   		sysfs_remove_group(&asus_armoury.fw_attr_kset->kobj, &mini_led_mode_attr_group);
>   err_remove_file:
> +	sysfs_remove_file(&asus_armoury.fw_attr_kset->kobj, &requires_fan_curve.attr);
>   	sysfs_remove_file(&asus_armoury.fw_attr_kset->kobj, &pending_reboot.attr);
>   err_destroy_kset:
>   	kset_unregister(asus_armoury.fw_attr_kset);
> @@ -1161,6 +1175,7 @@ static void __exit asus_fw_exit(void)
>   	if (asus_armoury.mini_led_dev_id)
>   		sysfs_remove_group(&asus_armoury.fw_attr_kset->kobj, &mini_led_mode_attr_group);
>   
> +	sysfs_remove_file(&asus_armoury.fw_attr_kset->kobj, &requires_fan_curve.attr);
>   	sysfs_remove_file(&asus_armoury.fw_attr_kset->kobj, &pending_reboot.attr);
>   	kset_unregister(asus_armoury.fw_attr_kset);
>   	device_destroy(&firmware_attributes_class, MKDEV(0, 0));