Re: [PATCH] platform/x86: asus-wmi: do not enforce a battery charge threshold

[Denis Benato <benato.denis96@gmail.com>]

On 3/4/26 17:07, Antheas Kapenekakis wrote:
> On Wed, 4 Mar 2026 at 14:52, Denis Benato <denis.benato@linux.dev> wrote:
>>
>> On 3/4/26 14:39, Antheas Kapenekakis wrote:
>>> On Wed, 4 Mar 2026 at 14:37, Denis Benato <denis.benato@linux.dev> wrote:
>>>> On 3/4/26 14:30, Antheas Kapenekakis wrote:
>>>>> On Wed, 4 Mar 2026 at 14:26, Denis Benato <denis.benato@linux.dev> wrote:
>>>>>> Users are complaining for the battery limit being reset at 100% during
>>>>>> the boot process while the general consensus appears to not apply
>>>>>> unsolecited hardware changes, therefore stop resetting the battery
>>>>> *unsolicited. But I would rephrase to using this causes the device to
>>>>> reset its limits on boot, which might have been set by e.g. windows so
>>>>> if userspace is not aware to restore them, this causes a functionality
>>>>> degradation. This is the case with the current implementation by KDE.
>>>>>
>>>>>> charge limit at boot and return -ENODATA on charge_end_threshold to
>>>>>> signal for an unknown limit.
>>>>>>
>>>>>> Suggested-by: Antheas Kapenekakis <lkml@antheas.dev>
>>>>>> Suggested-by: Derek J. Clark <derekjohn.clark@gmail.com>
>>>>>> Signed-off-by: Denis Benato <denis.benato@linux.dev>
>>>>>> ---
>>>>>>  drivers/platform/x86/asus-wmi.c | 13 ++++++++-----
>>>>>>  1 file changed, 8 insertions(+), 5 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
>>>>>> index 6ba49bd375df..dc330a8ee2f2 100644
>>>>>> --- a/drivers/platform/x86/asus-wmi.c
>>>>>> +++ b/drivers/platform/x86/asus-wmi.c
>>>>>> @@ -1557,7 +1557,10 @@ static ssize_t charge_control_end_threshold_show(struct device *device,
>>>>>>                                                  struct device_attribute *attr,
>>>>>>                                                  char *buf)
>>>>>>  {
>>>>>> -       return sysfs_emit(buf, "%d\n", charge_end_threshold);
>>>>>> +       if ((charge_end_threshold >= 0) && (charge_end_threshold <= 100))
>>>>>> +               return sysfs_emit(buf, "%d\n", charge_end_threshold);
>>>>>> +
>>>>>> +       return -ENODATA;
>>>>> Please verify this does not cause KDE to display a warning and block
>>>>> modifying the energy consumption. If it does as has been my
>>>>> experience, communicate with KDE devs or Gnome (if it has a similar
>>>>> issue) and block this from merging until there is a solution from
>>>>> their side.
>>>> KDE doesn't yet allow to modify that value as upower is not picking up batteries
>>>> with only end_threshold by default. Discussion is ongoing:
>>>>
>>>> https://gitlab.freedesktop.org/upower/upower/-/merge_requests/308
>>> I have tested this exact patch you posted on my Z13 last November. KDE
>>> does pick it up and display a warning.
>> Displaying a warning about the current limit not being recognised is what
>> is expected and correct behavior, not an ABI change: software isn't breaking.
>>
>> You talked about setting (as in writing) the limit and that, as of now
>> (at least in KDE) is not possible.
> This is not true. Powerdevil supports the Asus driver and has done so
> for at least a year.
>
> The setting is under "Power Management -> Advanced Power Settings". On
> mainline it works properly but resets after every reboot due to this
> bug.

I never noticed it... Interesting... well thank you.

> With your patch applied, at least with -ENODATA there is no error. KDE
> defaults to 50%. So perhaps this could be doable to merge, -EIO made
> it fail. If you verify Gnome works properly or just does not support
> battery limits, but actually verify it mind you, this should be good
> to merge.
Alright I will test gnome and cosmic and will let you know. Thanks
for covering KDE!
> Antheas
>
>
> Antheas
>
>> There already exists widely in use software that changes the battery
>> level when started setting it to the previous value, so that warning
>> is not to be seen; moreover said class of software is going to earn
>> a new entry so I don't see any problem here.
>>
>> Perhaps Ilpo has some more insights on the matter.
>>
>> In addition to that, after the removal from the kernel of acpi_platform
>> asus-wmi ABI are going to change anyway, regardless of what I do.
>>> Which is why I settled with sending a fake 100 value instead and never
>>> upstreamed it.
>>>
>>> Antheas
>>>
>>>> since it has never worked there is nothing to break.
>>>>> Returning an error from this function when there is proper function is
>>>>> a slight ABI change compared to current drivers that implement this
>>>>> method.
>>>>>
>>>>> Thanks,
>>>>> Antheas
>>>>>
>>>>>>  }
>>>>>>
>>>>>>  static DEVICE_ATTR_RW(charge_control_end_threshold);
>>>>>> @@ -1580,11 +1583,11 @@ static int asus_wmi_battery_add(struct power_supply *battery, struct acpi_batter
>>>>>>                 return -ENODEV;
>>>>>>
>>>>>>         /* The charge threshold is only reset when the system is power cycled,
>>>>>> -        * and we can't get the current threshold so let set it to 100% when
>>>>>> -        * a battery is added.
>>>>>> +        * and we can't read the current threshold, however the majority of
>>>>>> +        * platforms retains it, therefore signal the threshold as unknown
>>>>>> +        * until user explicitly sets it to a new value.
>>>>>>          */
>>>>>> -       asus_wmi_set_devstate(ASUS_WMI_DEVID_RSOC, 100, NULL);
>>>>>> -       charge_end_threshold = 100;
>>>>>> +       charge_end_threshold = -1;
>>>>>>
>>>>>>         return 0;
>>>>>>  }
>>>>>> --
>>>>>> 2.53.0
>>>>>>
>>>>>>