From: Thomas Koch <linrunner@gmx.net>
To: Hans de Goede <hdegoede@redhat.com>, Sebastian Reichel <sre@kernel.org>
Cc: "Nicolo' Piazzalunga" <nicolopiazzalunga@gmail.com>,
"platform-driver-x86@vger.kernel.org"
<platform-driver-x86@vger.kernel.org>,
"Mark Pearson" <markpearson@lenovo.com>,
"Nitin Joshi1" <njoshi1@lenovo.com>,
"jwrdegoede@fedoraproject.org" <jwrdegoede@fedoraproject.org>,
"smclt30p@gmail.com" <smclt30p@gmail.com>,
"Barnabás Pőcze" <pobrn@protonmail.com>
Subject: Re: [PATCH 1/3] thinkpad_acpi: add support for force_discharge
Date: Sat, 17 Apr 2021 13:49:46 +0200 [thread overview]
Message-ID: <a2d850e9-789d-54e8-e098-1a0829504031@gmx.net> (raw)
In-Reply-To: <6f58903f-5219-9aff-78ca-33687e2e4147@redhat.com>
Hi Hans,
from a userspace perspective, I don't think it's optimal to combine the
two features and the status. For example, how do I find out which one is
available?
I have to test the writability of status and then still don't know which
one is available. Seeing if force_discharge or inhibit_charge are there
is much simpler.
And then enabling that: triggering force_discharge by writing
"Discharging" is ok. But for inhibit_charge we would need a new status,
something like "Charging inhibited". This then causes problems for the
existing userspace, says: upowerd could not handle it. You remember the
"Not charging" patch from Ognen?
--
Freundliche Grüße / Kind regards,
Thomas Koch
Mail : linrunner@gmx.net
Web : https://linrunner.de/tlp
On 13.04.21 10:05, Hans de Goede wrote:
> Hi,
>
> On 4/9/21 8:33 PM, Thomas Koch wrote:
>> Hi,
>>
>> On 08.04.21 15:51, Sebastian Reichel wrote:
>>
>>> IIUIC you have 'force_discharge', which basically means the system
>>> is running from battery power despite an AC adapter being connected
>>> and 'inhibit_discharge', which inhibits charging, so system does not
>>> charge battery when AC is connected, but uses AC to supply itself
>>> (so battery is idle)?
>>>
>>> We already have this kind of features on embedded systems (which
>>> often provide all kind of charger details). Those drivers solve
>>> this by having a writable 'status' property in the charger device:
>>>
>>> What: /sys/class/power_supply/<supply_name>/status
>>> Date: May 2007
>>> Contact: linux-pm@vger.kernel.org
>>> Description:
>>> Represents the charging status of the battery. Normally this
>>> is read-only reporting although for some supplies this can be
>>> used to enable/disable charging to the battery.
>>>
>>> Access: Read, Write
>>>
>>> Valid values:
>>> "Unknown", "Charging", "Discharging",
>>> "Not charging", "Full"
>>>
>>> If I do not miss anything writing "Discharging" is the same as forced
>>> discharge and "Not Charging" (AKA Idle) is the same as your inhibit feature.
>>
>> There are ThinkPads with two batteries (BAT0, BAT1) and the hardware
>> allows to select which one to discharge. An approach through
>> /sys/class/power_supply/AC/status won't cover this.
>
> The mentioned status strings come from /sys/class/power_supply/VAT#/status,
> rather then from /sys/class/power_supply/AC/status.
>
> There is one problem though, which is that the status attribute is being
> managed by drivers/acpi/battery.c. There is infra for a driver like
> the thinkpad_apci driver to add new attributes to a power_supply but
> AFAIK there is no infra to say intercept writes to an attribute where
> the reading is handled by another driver.
>
> I guess we could add some special hook to allow another driver to
> intercept status writes.
>
> Sebastian, what is your take on this ?
>
> Regards,
>
> Hans
>
next prev parent reply other threads:[~2021-04-17 11:50 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-17 14:01 [PATCH 1/3] thinkpad_acpi: add support for force_discharge Nicolo' Piazzalunga
2021-04-07 10:24 ` Hans de Goede
2021-04-07 10:33 ` Barnabás Pőcze
2021-04-08 13:51 ` Sebastian Reichel
2021-04-08 18:18 ` Thomas Koch
2021-04-09 18:33 ` Thomas Koch
2021-04-13 8:05 ` Hans de Goede
2021-04-17 11:49 ` Thomas Koch [this message]
2021-04-17 17:03 ` Hans de Goede
2021-05-19 14:45 ` Nicolo' Piazzalunga
2021-04-07 12:19 ` Thomas Koch
2021-04-07 17:48 ` [External] " Mark Pearson
[not found] ` <VI1PR09MB2302B7C3AD8014CC98D36AA595759@VI1PR09MB2302.eurprd09.prod.outlook.com>
2021-04-12 17:10 ` Mark Pearson
2021-09-27 13:59 ` Mark Pearson
2021-09-27 15:00 ` Nicolò Piazzalunga
2021-09-27 15:12 ` Hans de Goede
2021-09-27 16:50 ` [External] " Mark Pearson
2021-09-29 5:47 ` Thomas Koch
2021-09-29 9:55 ` Hans de Goede
2021-09-29 10:45 ` Thomas Koch
2021-09-29 10:56 ` Hans de Goede
2021-09-29 13:45 ` [External] " Mark Pearson
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