linux-kernel - Re: [PATCH v4 3/3] Documentation: power: rt9471: Document exported sysfs entries

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Date:   Mon, 12 Sep 2022 13:12:01 +0200
From:   Sebastian Reichel <sebastian.reichel@...labora.com>
To:     cy_huang <u0084500@...il.com>
Cc:     robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        mazziesaccount@...il.com, alina_yu@...htek.com,
        cy_huang@...htek.com, alinayu829@...il.com,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/3] Documentation: power: rt9471: Document exported
 sysfs entries

Hi,

On Mon, Aug 29, 2022 at 11:06:31AM +0800, cy_huang wrote:
> From: ChiYuan Huang <cy_huang@...htek.com>
> 
> Document the settings exported by rt9471 charger driver through sysfs entries:
> - sysoff_enable
> - charge_term_enable
> - port_detect_enable
> 
> Signed-off-by: ChiYuan Huang <cy_huang@...htek.com>
> ---
>  Documentation/ABI/testing/sysfs-class-power | 44 +++++++++++++++++++++++++++++
>  1 file changed, 44 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-power b/Documentation/ABI/testing/sysfs-class-power
> index a9ce63c..1f8afe5 100644
> --- a/Documentation/ABI/testing/sysfs-class-power
> +++ b/Documentation/ABI/testing/sysfs-class-power
> @@ -768,3 +768,47 @@ Description:
>  
>  		Access: Read
>  		Valid values: 1-31
> +
> +What:		/sys/class/power_supply/rt9471-*/sysoff_enable
> +Date:		Sep 2022
> +KernelVersion:	6.1
> +Contact:	ChiYuan Huang <cy_huang@...htek.com>
> +Description:
> +		This entry allows enabling the sysoff mode of rt9471 charger devices.
> +		If enabled and the input is removed, the internal battery FET is turned
> +		off to reduce the leakage from the BAT pin. See device datasheet for details.
> +
> +		Access: Read, Write
> +		Valid values:
> +		- 1: enabled
> +		- 0: disabled

This is not a very good description of what the control does. When
do you expect users to control this?

> +What:		/sys/class/power_supply/rt9471-*/charge_term_enable
> +Date:		Sep 2022
> +KernelVersion:	6.1
> +Contact:	ChiYuan Huang <cy_huang@...htek.com>
> +Description:
> +		This entry allows enabling the charge termination function of rt9471 charger
> +		devices. If enabled, the battery charging current, and the battery voltage
> +		reachs charge termination condition, the internal battery FET will be turned off
> +		to optimize the battery life. See device datasheet for details.
> +
> +		Access: Read, Write
> +		Valid values:
> +		- 1: enabled
> +		- 0: disabled

Just write 0 to .../charge_term_current to disable it.
No need for a custom property.

> +What:		/sys/class/power_supply/rt9471-*/port_detect_enable
> +Date:		Sep 2022
> +KernelVersion:	6.1
> +Contact:	ChiYuan Huang <cy_huang@...htek.com>
> +Description:
> +		This entry allows enabling the USB BC12 port detect function of rt9471 charger
> +		devices. If enabled and VBUS is inserted, device will start to do the BC12
> +		port detect and report the usb port type when port detect is done. See
> +		datasheet for details.
> +
> +		Access: Read, Write
> +		Valid values:
> +		- 1: enabled
> +		- 0: disabled

Why would one want to disable this?
Can't the driver just enable it unconditionally?

-- Sebastian

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