On Fri, Apr 29, 2022 at 7:41 PM Maximilian Luz <luzmaximilian@xxxxxxxxx> wrote: > > Microsoft Surface devices have a limiter that sets a fixed maximum > charge capacity for the battery. When that maximum capacity has been > reached, charging stops. In that case, _BST returns a battery state > field with both "charging" and "discharging" bits cleared. The battery > driver, however, returns "unknown" as status. > > This seems to be the same behavior as observed on the ThinkPads, so > let's use the same quirk to handle that. > > Signed-off-by: Maximilian Luz <luzmaximilian@xxxxxxxxx> > --- > > For what it's worth, I don't think the ACPI spec explicitly states that > any of the status bits need to be set, or that there are only the > "charging" and "discharging" states. As far as I can tell, ACPI only > states: > > Notice that the Charging bit and the Discharging bit are mutually > exclusive and must not both be set at the same time. Even in > critical state, hardware should report the corresponding > charging/discharging state. > > But that does not exclude the case that no bit is set. So, strictly > going by spec, I don't think it's necessary to put all of this behind a > quirk. I think that this should be covered by the patch I've just applied: https://patchwork.kernel.org/project/linux-acpi/patch/20220427154053.499203-1-wse@xxxxxxxxxxxxxxxxxxx/ Shouldn't it? > --- > drivers/acpi/battery.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c > index dc208f5f5a1f..1c88504aae5b 100644 > --- a/drivers/acpi/battery.c > +++ b/drivers/acpi/battery.c > @@ -1152,6 +1152,19 @@ static const struct dmi_system_id bat_dmi_table[] __initconst = { > DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad"), > }, > }, > + { > + /* > + * Microsoft Surface devices have an optional "battery > + * limiter". Due to this, there is a "Not Charging" state > + * similar to the one on the Lenovo ThinkPads, described above. > + */ > + .callback = battery_quirk_not_charging, > + .ident = "Microsoft Surface", > + .matches = { > + DMI_MATCH(DMI_SYS_VENDOR, "Microsoft Corporation"), > + DMI_MATCH(DMI_PRODUCT_NAME, "Surface"), > + }, > + }, > { > /* Microsoft Surface Go 3 */ > .callback = battery_notification_delay_quirk, > -- > 2.36.0 >
