Revert commit c68f0676ef ("ACPI / battery: Add quirk for Asus
GL502VSK and UX305LA") and commit 4446823e25 ("ACPI / battery: Add
quirk for Asus UX360UA and UX410UAK").
On many many Asus products, the battery is sometimes reported as
charging or discharging even when it is full and you are on AC power.
This change quirked the kernel to avoid advertising the discharging
state when this happens on 4 laptop models, under the belief that
this was incorrect information. I presume it originates from user
reports who are confused that their battery status icon says that it
is discharging.
However, the reported information is indeed correct, and the quirk
approach taken is inadequate and more thought is needed first.
Specifically:
1. It only quirks discharging state, not charging
2. There are so many different Asus products and DMI naming variants
within those product families that behave this way; Linux could
grow to quirk hundreds of products and still not even be close at
"winning" this battle.
3. Asus previously clarified that this behaviour is intentional. The
platform will periodically do a partial discharge/charge cycle
when the battery is full, because this is one way to extend the
lifetime of the battery (leaving a battery at 100% charge and
unused will decrease its usable capacity over time).
My understanding is that any decent consumer product will have
this behaviour, but it appears that Asus is different in that
they expose this info through ACPI.
However, the behaviour seems correct. The ACPI spec does not
suggest in that the platform should hide the truth. It lets you
report that the battery is full of charge, and discharging, and
with external power connected; and Asus does this.
4. In terms of not confusing the user, this seems like something that
could/should be handled by userspace, which can also detect these
same (accurate) conditions in the general case.
Revert this quirk before it gets included in a release, while we look
for better approaches.
Signed-off-by: Daniel Drake <drake@endlessm.com>
Acked-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
82bf43b291