linux-kernel - Re: [PATCH v2 1/8] power: supply: core: Add resistance power supply property

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Message-ID: <b7m55sjc2rtvtelvez6sxnjvdostvxmfjhhsr4uxhyhh4bxrcd@xmioz2bsgis2>
Date: Sun, 22 Jun 2025 03:26:50 +0200
From: Sebastian Reichel <sebastian.reichel@...labora.com>
To: fenglin.wu@....qualcomm.com
Cc: Bjorn Andersson <andersson@...nel.org>, 
	Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Subbaraman Narayanamurthy <subbaraman.narayanamurthy@....qualcomm.com>, David Collins <david.collins@....qualcomm.com>, 
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
	kernel@....qualcomm.com, devicetree@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH v2 1/8] power: supply: core: Add resistance power supply
 property

Hi,

On Fri, May 30, 2025 at 03:35:06PM +0800, Fenglin Wu via B4 Relay wrote:
> From: Fenglin Wu <fenglin.wu@....qualcomm.com>
> 
> Some battery drivers provide the ability to export resistance as a
> parameter. Add resistance power supply property for that purpose.

This is missing some information and the naming is bad.

Which resistance (I suppose battery internal resistance)?

That is heavily dependent on the battery temperature. So this needs
to document if this is for the current temperature or for some
specific one.

-- Sebastian

> Signed-off-by: Fenglin Wu <fenglin.wu@....qualcomm.com>
> ---
>  Documentation/ABI/testing/sysfs-class-power | 10 ++++++++++
>  drivers/power/supply/power_supply_sysfs.c   |  1 +
>  include/linux/power_supply.h                |  1 +
>  3 files changed, 12 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-power b/Documentation/ABI/testing/sysfs-class-power
> index 560124cc31770cde03bcdbbba0d85a5bd78b15a0..22a565a6a1c509461b8c483e12975295765121d6 100644
> --- a/Documentation/ABI/testing/sysfs-class-power
> +++ b/Documentation/ABI/testing/sysfs-class-power
> @@ -552,6 +552,16 @@ Description:
>  			Integer > 0: representing full cycles
>  			Integer = 0: cycle_count info is not available
>  
> +What:		/sys/class/power_supply/<supply_name>/resistance
> +Date:		May 2025
> +Contact:	linux-arm-msm@...r.kernel.org
> +Description:
> +		Reports the resistance of the battery power supply.
> +
> +		Access: Read
> +
> +		Valid values: Represented in microohms
> +
>  **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 a438f7983d4f6a832e9d479184c7c35453e1757c..dd829148eb6fda5dcd7eab53fc70f99081763714 100644
> --- a/drivers/power/supply/power_supply_sysfs.c
> +++ b/drivers/power/supply/power_supply_sysfs.c
> @@ -220,6 +220,7 @@ static struct power_supply_attr power_supply_attrs[] __ro_after_init = {
>  	POWER_SUPPLY_ATTR(MANUFACTURE_YEAR),
>  	POWER_SUPPLY_ATTR(MANUFACTURE_MONTH),
>  	POWER_SUPPLY_ATTR(MANUFACTURE_DAY),
> +	POWER_SUPPLY_ATTR(RESISTANCE),
>  	/* 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 c4cb854971f53a244ba7742a15ce7a5515da6199..de3e88810e322546470b21258913abc7707c86a7 100644
> --- a/include/linux/power_supply.h
> +++ b/include/linux/power_supply.h
> @@ -174,6 +174,7 @@ enum power_supply_property {
>  	POWER_SUPPLY_PROP_MANUFACTURE_YEAR,
>  	POWER_SUPPLY_PROP_MANUFACTURE_MONTH,
>  	POWER_SUPPLY_PROP_MANUFACTURE_DAY,
> +	POWER_SUPPLY_PROP_RESISTANCE,
>  	/* Properties of type `const char *' */
>  	POWER_SUPPLY_PROP_MODEL_NAME,
>  	POWER_SUPPLY_PROP_MANUFACTURER,
> 
> -- 
> 2.34.1
> 
> 

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