Re: sysfs charge thresholds for ThinkPads (and possibly others), preparation for second try

[Sebastian Reichel <sre@kernel.org>]

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Hi,

On Tue, Jul 07, 2015 at 11:07:28PM +0200, Julian Andres Klode wrote:
> Hi everyone (Thinkpad-ACPI, ACPI, and Power supply maintainers),
> 
> some might know that I presented a patch set adding support for
> charge thresholds to thinkpad_acpi about 1.5 years ago. 

Can you provide a link to the patch set?

> Back then, one of the major rejections was that the functionality
> for setting charge thresholds should be integrated into the
> power supply stack somehow. I did not know who to contact back
> then, but know I re-read MAINTAINERS and found all your addresses,
> so I give it a second try.
> 
> One issue with just integrating it in the current battery
> directories would be that ThinkPads are able to set charge
> thresholds for batteries that are currently not inserted.

So the power supply device should be kept with
POWER_SUPPLY_PROP_PRESENT being disabled (and most properties
returning -ENODATA). The ACPI SBS driver seems to implement
POWER_SUPPLY_PROP_PRESENT, but I didn't test it.

> Back then I wrote:
> > The next step is to integrate this properly with power supply
> > and/or acpi battery. One way would be to add additional power
> > supply properties and then add get/set_property() pointers to
> > the acpi battery which it can fall back to if it does not support
> > a requested property (and we would locate the ACPI battery and
> > set those pointers to new thinkpad_acpi functions).
> 
> If you, the ACPI and power supply people, have any preferred
> way (or any idea at all how) to proceed, that would be useful,
> so I don't start working on it again, and then somebody does
> not like it.

Adding charging thresholds as power_supply_property sounds
fine to me.

-- Sebastian

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