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

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Message-Id: <20211123232704.25394-1-linux@weissschuh.net>
Date:   Wed, 24 Nov 2021 00:27:00 +0100
From:   Thomas Weißschuh <linux@...ssschuh.net>
To:     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:     Thomas Weißschuh <linux@...ssschuh.net>,
        linux-kernel@...r.kernel.org, linrunner@....net, bberg@...hat.com,
        hadess@...ess.net, markpearson@...ovo.com,
        nicolopiazzalunga@...il.com, njoshi1@...ovo.com, smclt30p@...il.com
Subject: [PATCH 0/4] power: supply: add charge_behaviour property (force-discharge, inhibit-charge)

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:

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?

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/

v1: https://lore.kernel.org/lkml/20211113104225.141333-1-linux@weissschuh.net/
v1 -> v2:

* Use sysfs_emit-APIs instead of plain sprintf
* More cecks for actual feature availability
* Validation of the written values
* Read inhibit-charge via BICG instead of PSSG (peak shift state)
* Don't mangle error numbers in charge_behaviour_store()

Open points:

Thomas Koch has observed that on a T450s with two batteries
inhibit-charge on BAT0 will affect both batteries and for BAT1 it is ignored
entirely, this seems to be a bug in the EC.
On my T460s with two batteries it works correctly.

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        | 191 +++++++++++++++++++-
 drivers/power/supply/power_supply_sysfs.c   |  51 ++++++
 include/linux/power_supply.h                |  16 ++
 4 files changed, 268 insertions(+), 4 deletions(-)

base-commit: 66f4beaa6c1d28161f534471484b2daa2de1dce0
-- 
2.34.0