linux-kernel - Re: [RFC PATCH] leds: multicolor: Add sysfs interface definition

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Date:   Wed, 30 Jan 2019 20:37:44 +0100
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Dan Murphy <dmurphy@...com>, robh+dt@...nel.org, pavel@....cz
Cc:     linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org
Subject: Re: [RFC PATCH] leds: multicolor: Add sysfs interface definition

Hi Dan,

Thank you for the RFC.

One vital thing is missing - documentation of brightness file must
be updated to define its semantics for LED multi color class.

Either we need brightness-model file returning only "onoff" option
available, or, for time being, fix the max_brightness for LED multi
color class to 1 (which will map to max intensity level for each color).

Best regards,
Jacek Anaszewski

On 1/30/19 7:30 PM, Dan Murphy wrote:
> Add a documentation of LED Multicolor LED class specific
> sysfs attributes.
> 
> Signed-off-by: Dan Murphy <dmurphy@...com>
> ---
>   .../ABI/testing/sysfs-class-led-multicolor    | 38 +++++++++++++++++++
>   1 file changed, 38 insertions(+)
>   create mode 100644 Documentation/ABI/testing/sysfs-class-led-multicolor
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-led-multicolor b/Documentation/ABI/testing/sysfs-class-led-multicolor
> new file mode 100644
> index 000000000000..19f8da9b150e
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-led-multicolor
> @@ -0,0 +1,38 @@
> +What:		/sys/class/leds/<led>/color/sync_enable
> +Date:		January 2019
> +KernelVersion:	5.0
> +Contact:	Dan Murphy <dmurphy@...com>
> +Description:	read/write
> +		Writing a 1 to this file will enable the sychronization of all
> +		the defined color LEDs within the LED node.  Writing a 0 to
> +		this file will disable syncing.
> +
> +What:		/sys/class/leds/<led>/color/sync
> +Date:		January 2019
> +KernelVersion:	5.0
> +Contact:	Dan Murphy <dmurphy@...com>
> +Description:	write only
> +		Writing a 1 to this file while sync_enable is set to 1 will
> +		synchronize all defined LEDs within the LED node.  All LEDs
> +		defined will be configured based on the brightness that has
> +		been requested.
> +
> +		If sync_enable is set to 0 then writing a 1 to sync has no
> +		affect on the LEDs.
> +
> +What:		/sys/class/leds/<led>/color/<led color>
> +Date:		January 2019
> +KernelVersion:	5.0
> +Contact:	Dan Murphy <dmurphy@...com>
> +Description:	read/write
> +		These files are dynamically created based on the colors defined
> +		by the registrar of the class.
> +		The led color(s) can be but not limited to red, green, blue,
> +		white, amber and violet.  If sync is enabled then writing the
> +		brightness value of the LED is deferred until a 1 is
> +		written to /sys/class/leds/<led>/color/sync.  If syncing is
> +		disabled then the LED brightness value will be written
> +		immediately to the LED driver.
> +
> +		The value of the color is from 0 to
> +		/sys/class/leds/<led>/max_brightness.
>