Re: [PATCH 0/4] power: supply: add charge_behaviour property (force-discharge, inhibit-charge)

[Thomas Koch]

Hi Thomas,

On 17.11.21 18:57, Thomas Weißschuh wrote:
> On 2021-11-16 17:56+0100, Thomas Koch wrote:
> > thank you very much for working on this. It is high time that we leave
> > external kernel modules for ThinkPads behind us.
> >
> > On 13.11.21 11:42, Thomas Weißschuh wrote:
> > > Hi,
> > >
> > > this series adds support for the charge_behaviour property to the power
> > > subsystem and thinkpad_acpi driver.
> > >
> > > As thinkpad_acpi has to use the 'struct power_supply' created by the generic
> > > ACPI driver it has to rely on custom sysfs attributes instead of proper
> > > power_supply properties to implement this property.
> > >
> > > Patch 1: Adds the power_supply documentation and basic public API
> > > Patch 2: Adds helpers to power_supply core to help drivers implement the
> > >     charge_behaviour attribute
> > > Patch 3: Adds support for force-discharge to thinkpad_acpi.
> > > Patch 4: Adds support for inhibit-discharge to thinkpad_acpi.
> > >
> > > Patch 3 and 4 are largely taken from other patches and adapted to the new API.
> > > (Links are in the patch trailer)
> > >
> > > Ognjen Galic, Nicolo' Piazzalunga, Thomas Koch:
> > >
> > > Your S-o-b is on the original inhibit_charge and force_discharge patches.
> > > I would like to add you as Co-developed-by but to do that it will also require
> > > your S-o-b. Could you give your sign-offs for the new patches, so you can be
> > > properly attributed?
> > S-o-b/Co-developed-by/Tested-by is fine with me.
> >
> > I tested your patches.
> >
> > Hardware:
> >
> > - ThinkPad X220, BAT0
> > - ThinkPad T450s, BAT0+BAT1
> > - ThinkPad X1C6, BAT0
> >
> > Test Results:
> >
> > 1. force-discharge
> >
> > Everythings works as expected
> > - Writing including disengaging w/ "auto" : OK
> > - Reading: OK
> >
> > - Battery discharging: OK
> > - Disengaging with "auto": OK
> >
> > 2. inhibit-charge
> >
> > Works as expected:
> > - Writing: OK
> >
> > - Disengaging with "auto": OK
> >
> >
> > Discrepancies:
> > - Battery charge inhibited: BAT0 OK, BAT1 no effect e.g. continues charging
> > - Reading: always returns "auto"
>
> I tested it on a T460s with two batteries and there inhibit-charge works
> fine for both batteries.
> What does not work is setting force-discharge for both batteries at the same
> time.
> This makes somewhat sense as on a physical level probably only one of them can
> be used at a time.

My experience confirms your consideration. The ThinkPad battery circuit
can handle exactly one battery at a time i.e.
- Charging, AC connected
- Forced discharging,  AC connected
- Discharging, AC disconnected
The other battery is always idle during this time.

> Mark Pearson: Could you confirm that this is the intended behaviour?
>
> In my changes queued for v2 of the series[0] I added validation of the written
> settings and an EIO is now reported if the settings were not applied, so this
> should help userspace handle this situatoin.
>
> The plan is to submit v2 after the first round of review for the core PM
> changes.

Please wait until i'm finished with testing your queued v2. I am getting
errors here and would first like to rule out homemade problems with my
kernel build and/or base version.

> [0] https://git.sr.ht/~t-8ch/linux/tree/charge-control


--
Freundliche Grüße / Kind regards,
Thomas Koch

Mail : linrunner@xxxxxxx
Web  : https://linrunner.de/tlp