linux-kernel - Re: [PATCH 4/4] devicetree: Add led-backlight binding

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Message-ID: <0a2c7f84-ea1f-cab2-c812-b5cefed1f517@ti.com>
Date:   Tue, 2 Jul 2019 13:11:58 +0200
From:   Jean-Jacques Hiblot <jjhiblot@...com>
To:     Daniel Thompson <daniel.thompson@...aro.org>
CC:     <jacek.anaszewski@...il.com>, <pavel@....cz>, <robh+dt@...nel.org>,
        <mark.rutland@....com>, <lee.jones@...aro.org>,
        <jingoohan1@...il.com>, <dmurphy@...com>,
        <linux-leds@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>, <tomi.valkeinen@...com>,
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH 4/4] devicetree: Add led-backlight binding

Daniel,

On 02/07/2019 11:58, Daniel Thompson wrote:
> On Mon, Jul 01, 2019 at 05:14:23PM +0200, Jean-Jacques Hiblot wrote:
>> From: Tomi Valkeinen <tomi.valkeinen@...com>
>>
>> Add DT binding for led-backlight.
> I think the patchset is in the wrong order; the DT bindings
> documentation should appear *before* the binding is
> implemented (amoung other things this prevent transient checkpatch
> warnings as the patchset is applied).
>
ok
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...com>
>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@...com>
>> Cc: devicetree@...r.kernel.org
>> ---
>>   .../video/backlight/led-backlight.txt         | 39 +++++++++++++++++++
>>   1 file changed, 39 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/video/backlight/led-backlight.txt
>>
>> diff --git a/Documentation/devicetree/bindings/video/backlight/led-backlight.txt b/Documentation/devicetree/bindings/video/backlight/led-backlight.txt
>> new file mode 100644
>> index 000000000000..216cd52d624a
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/video/backlight/led-backlight.txt
>> @@ -0,0 +1,39 @@
>> +led-backlight bindings
>> +
>> +The node of the backlight driver IS the node of the LED.
>> +
>> +Required properties:
>> +  - compatible: "led-backlight"
>> +  - brightness-levels: Array of distinct LED brightness levels. These
>> +      are in the range from 0 to 255, passed to the LED class driver.
>> +  - default-brightness-level: the default brightness level (index into the
>> +      array defined by the "brightness-levels" property)
> I think brightness-levels and default-brightness-level could be
> optional properties since a default 1:1 mapping seems reasonable given
> how constrained the LED brightness values are.

That is probably a good idea. Expect it in v2

Thanks,

JJ

>
>
> Daniel.
>
>
>> +
>> +Optional properties:
>> +  - power-supply: regulator for supply voltage
>> +  - enable-gpios: contains a single GPIO specifier for the GPIO which enables
>> +                  and disables the backlight (see GPIO binding[0])
>> +
>> +[0]: Documentation/devicetree/bindings/gpio/gpio.txt
>> +
>> +Example:
>> +
>> +led_ctrl {
>> +	red_led@1 {
>> +	        label = "red";
>> +		reg = <1>;
>> +	}
>> +
>> +	backlight_led@2 {
>> +		function = LED_FUNCTION_BACKLIGHT;
>> +		reg = <2>;
>> +
>> +		compatible = "led-backlight";
>> +
>> +		brightness-levels = <0 4 8 16 32 64 128 255>;
>> +		default-brightness-level = <6>;
>> +
>> +		power-supply = <&vdd_bl_reg>;
>> +		enable-gpios = <&gpio 58 0>;
>> +	};
>> +};
>> -- 
>> 2.17.1
>>