* Re: [PATCH] Documentation: sysfs-class-power: Update Long_Life description
From: Hans de Goede @ 2026-08-08 13:37 UTC (permalink / raw)
To: Derek J. Clark, Sebastian Reichel
Cc: Pierre-Loup A . Griffais, linux-pm, linux-kernel, linux-api
In-Reply-To: <20260803210720.23844-1-derekjohn.clark@gmail.com>
Hi Derek,
On 3-Aug-26 23:07, Derek J. Clark wrote:
> While adding charge limiting support to the Lenovo WMI drivers, there
> was some back and forth about whether charge_types or
> charge_control_end_threshold was the appropriate attribute to expose a
> battery charge limiting toggle that is fixed in the BIOS. The confusion
> arose because the charge_control_end_threshold description closely
> matches the functional change the hardware is making, while the
> charge_types functionality better suits the actual an on/off toggle that
> occurs in the BIOS. This specific scenario is not explicitly enumerated
> in the documentation, though it is fairly common.
>
> Given that the original intention was to use it this way[1],[2], and that
> the samsung-laptop[3], ideapad-laptop[4], and lenovo-wmi-other[5] drivers
> all use the convention of charge_types with an exposed Long_Life and
> Standard value for this, codify it in the Documentation to avoid confusion
> in the future.
>
> [1] https://lore.kernel.org/linux-pm/49993a42-aa91-46bf-acef-4a089db4c2db@redhat.com/
> [2] https://lore.kernel.org/platform-driver-x86/20241209204051.8786-1-hdegoede@redhat.com/
> [3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=de2884c6cdd3d133704ce37393590dd1c761500c
> [4] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=da8f2708f9b69707f4efeb432a18395e46b4666f
> [5] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9ca8fc065b88b327acbfdc33454efea391639716
>
> Suggested-by: Hans de Goede <hansg@kernel.org>
> Signed-off-by: Derek J. Clark <derekjohn.clark@gmail.com>
Thank you for updating the docs, patch looks good to me:
Reviewed-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Regards,
Hans
> ---
> Documentation/ABI/testing/sysfs-class-power | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-power b/Documentation/ABI/testing/sysfs-class-power
> index 5641f1fd5fd6..98b389845d1e 100644
> --- a/Documentation/ABI/testing/sysfs-class-power
> +++ b/Documentation/ABI/testing/sysfs-class-power
> @@ -365,9 +365,12 @@ Contact: linux-pm@vger.kernel.org
> Description:
> Represents a battery percentage level, above which charging will
> stop. Not all hardware is capable of setting this to an arbitrary
> - percentage. Drivers will round written values to the nearest
> - supported value. Reading back the value will show the actual
> - threshold set by the driver.
> + value, instead providing different minimum, maximum, or step
> + values. Drivers will round written values to the nearest supported
> + value. Reading back the value will show the actual threshold set
> + by the driver. For hardware that only supports a single fixed
> + value, use charge_types with a value of "Long Life" (vs "Standard")
> + instead'
>
> Access: Read, Write
>
> @@ -398,8 +401,9 @@ Description:
> when to start and stop charging. Advanced users
> can use this to drastically extend battery life.
> Long Life:
> - The charger reduces its charging rate in order to
> - prolong the battery health.
> + The charger firmware reduces its charging rate and/or
> + maximum charging percentage to a hardware specified
> + fixed limit in order to prolong the battery health.
> Bypass:
> The charger bypasses the charging path around the
> integrated converter allowing for a "smart" wall
^ permalink raw reply
page: | prev (newer) | latest
- recent:[subjects (threaded)|topics (new)|topics (active)]
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox