Re: [PATCH v4 2/8] power: supply: core: Add state_of_health power supply property

Sebastian Reichel
2025-09-16T19:19:21Z

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Hi,

On Mon, Sep 15, 2025 at 04:49:54PM +0800, Fenglin Wu via B4 Relay wrote:
> From: Fenglin Wu <fenglin.wu@oss.qualcomm.com>
>
> Add state_of_health power supply property to represent battery
> health percentage.
>
> Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on Thinkpad T14S OLED
> Signed-off-by: Fenglin Wu <fenglin.wu@oss.qualcomm.com>
> ---
> Documentation/ABI/testing/sysfs-class-power | 15 +++++++++++++++
> drivers/power/supply/power_supply_sysfs.c | 1 +
> include/linux/power_supply.h | 1 +
> 3 files changed, 17 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-power b/Documentation/ABI/testing/sysfs-class-power
> index cea1a38f5a8fb754d4e6323967ef6cf2e20a68ce..04f82e3e33aad6e16dc4fbace066b5d26069bf44 100644
> --- a/Documentation/ABI/testing/sysfs-class-power
> +++ b/Documentation/ABI/testing/sysfs-class-power
> @@ -568,6 +568,21 @@ Description:
>
> Valid values: Represented in microohms
>
> +What: /sys/class/power_supply/<supply_name>/state_of_health
> +Date: August 2025
> +Contact: linux-arm-msm@vger.kernel.org
> +Description:
> + The state_of_health parameter quantifies the overall condition
> + of a battery as a percentage, reflecting its ability to deliver
> + rated performance relative to its original specifications. It is
> + dynamically computed using a combination of learned capacity
> + and impedance-based degradation indicators, both of which evolve
> + over the battery's lifecycle.

I think this should be extended by the following:

Note that the exact algorithms are kept secret by most battery
vendors and the value from different battery vendors cannot be
compared with each other as there is no vendor-agnostic definition
of "performance". Also this usually cannot be used for any
calculations (i.e. this is not the factor between charge_full and
charge_full_design).

-- Sebastian

> +
> + Access: Read
> +
> + Valid values: 0 - 100 (percent)
> +
> **USB Properties**
>
> What: /sys/class/power_supply/<supply_name>/input_current_limit
> diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
> index cfa8f90a88ebc8fc1c7447198f138e5d2e699e5a..d96a8578308e3af60cc1a352845662aa922c29b3 100644
> --- a/drivers/power/supply/power_supply_sysfs.c
> +++ b/drivers/power/supply/power_supply_sysfs.c
> @@ -221,6 +221,7 @@ static struct power_supply_attr power_supply_attrs[] __ro_after_init = {
> POWER_SUPPLY_ATTR(MANUFACTURE_MONTH),
> POWER_SUPPLY_ATTR(MANUFACTURE_DAY),
> POWER_SUPPLY_ATTR(INTERNAL_RESISTANCE),
> + POWER_SUPPLY_ATTR(STATE_OF_HEALTH),
> /* Properties of type `const char *' */
> POWER_SUPPLY_ATTR(MODEL_NAME),
> POWER_SUPPLY_ATTR(MANUFACTURER),
> diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
> index 8bc3b7a67eb5693a16db9b7d123e7881711c6bf4..ccb43fe44381965069dc3bd9505d45050b9b1bd8 100644
> --- a/include/linux/power_supply.h
> +++ b/include/linux/power_supply.h
> @@ -175,6 +175,7 @@ enum power_supply_property {
> POWER_SUPPLY_PROP_MANUFACTURE_MONTH,
> POWER_SUPPLY_PROP_MANUFACTURE_DAY,
> POWER_SUPPLY_PROP_INTERNAL_RESISTANCE,
> + POWER_SUPPLY_PROP_STATE_OF_HEALTH,
> /* Properties of type `const char *' */
> POWER_SUPPLY_PROP_MODEL_NAME,
> POWER_SUPPLY_PROP_MANUFACTURER,
>
> --
> 2.34.1
>
>

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