linux-kernel - Re: [PATCH v5 3/3] Documentation: power: rt9471: Document exported sysfs entries

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Date:   Fri, 16 Sep 2022 20:08:23 +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 v5 3/3] Documentation: power: rt9471: Document exported
 sysfs entries

Hi,

On Thu, Sep 15, 2022 at 12:30:15AM +0800, cy_huang wrote:
> From: ChiYuan Huang <cy_huang@...htek.com>
> 
> Document the settings exported by rt9471 charger driver through sysfs entries:
> - sysoff_enable
> - port_detect_enable
> 
> Signed-off-by: ChiYuan Huang <cy_huang@...htek.com>
> ---
> Since v5:
> - Recover all the change in sysfs-class-power.
> - New a sysfs-class-power-rt9471 file.
> - Remove 'charge_term_enable' sysfs entry, directly integrate it in
>   'charge_term_current' power supply property control.
> 
> ---
>  Documentation/ABI/testing/sysfs-class-power-rt9471 | 29 ++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-class-power-rt9471
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-power-rt9471 b/Documentation/ABI/testing/sysfs-class-power-rt9471
> new file mode 100644
> index 00000000..ad5b049
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-power-rt9471
> @@ -0,0 +1,29 @@
> +What:		/sys/class/power_supply/rt9471-*/sysoff_enable
> +Date:		Oct 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.
> +		It's commonly used when the product enter shipping stage.
> +
> +		Access: Read, Write
> +		Valid values:
> +		- 1: enabled
> +		- 0: disabled

I still fail to see why this needs to be controllable at runtime.
This looks like a hardware property. Are there any known products,
which need this disabled?

> +What:		/sys/class/power_supply/rt9471-*/port_detect_enable
> +Date:		Oct 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. Normally controlled when TypeC/USBPD port integrated.
> +
> +		Access: Read, Write
> +		Valid values:
> +		- 1: enabled
> +		- 0: disabled

So basically this depends on the hardware integration (e.g. it
should be disabled when power source is a DC barrel jack instead
of USB) and is not supposed to change at all during runtime? Then
the information wether it needs to be enabled should be derived
from the device tree.

-- Sebastian

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