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

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Date:   Tue, 16 Nov 2021 17:56:43 +0100
From:   Thomas Koch <linrunner@....net>
To:     Thomas Weißschuh <linux@...ssschuh.net>,
        linux-pm@...r.kernel.org, Sebastian Reichel <sre@...nel.org>,
        ibm-acpi-devel@...ts.sourceforge.net,
        platform-driver-x86@...r.kernel.org,
        Mark Gross <markgross@...nel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Henrique de Moraes Holschuh <hmh@....eng.br>
Cc:     linux-kernel@...r.kernel.org, bberg@...hat.com, hadess@...ess.net,
        markpearson@...ovo.com, nicolopiazzalunga@...il.com,
        njoshi1@...ovo.com, smclt30p@...il.com
Subject: Re: [PATCH 0/4] power: supply: add charge_behaviour property
 (force-discharge, inhibit-charge)

Hi Thomas,

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"

Note: the reading discrepancy may be related to Hans' remarks [1].

[1]
https://lore.kernel.org/all/09a66da1-1a8b-a668-3179-81670303ea37@redhat.com/

>
> Sebastian Reichel:
>
> Currently the series does not actually support the property as a proper
> powersupply property handled fully by power_supply_sysfs.c because there would
> be no user for this property.
>
> Previous discussions about the API:
>
> https://lore.kernel.org/platform-driver-x86/20211108192852.357473-1-linux@weissschuh.net/
> https://lore.kernel.org/platform-driver-x86/21569a89-8303-8573-05fb-c2fec29983d1@gmail.com/
>
> Thomas Weißschuh (4):
>    power: supply: add charge_behaviour attributes
>    power: supply: add helpers for charge_behaviour sysfs
>    platform/x86: thinkpad_acpi: support force-discharge
>    platform/x86: thinkpad_acpi: support inhibit-charge
>
>   Documentation/ABI/testing/sysfs-class-power |  14 ++
>   drivers/platform/x86/thinkpad_acpi.c        | 154 +++++++++++++++++++-
>   drivers/power/supply/power_supply_sysfs.c   |  51 +++++++
>   include/linux/power_supply.h                |  16 ++
>   4 files changed, 231 insertions(+), 4 deletions(-)
>
>
> base-commit: 66f4beaa6c1d28161f534471484b2daa2de1dce0
>
--
Freundliche Grüße / Kind regards,
Thomas Koch

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