linux-kernel - Re: [PATCH 1/2] leds: ncp5623: Add device tree binding documentation

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Date:	Wed, 22 Jun 2016 10:52:59 +0200
From:	Jacek Anaszewski <j.anaszewski@...sung.com>
To:	Florian Vaussard <florian.vaussard@...il.com>
Cc:	devicetree@...r.kernel.org, Richard Purdie <rpurdie@...ys.net>,
	Rob Herring <robh+dt@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
	Florian Vaussard <florian.vaussard@...g-vd.ch>
Subject: Re: [PATCH 1/2] leds: ncp5623: Add device tree binding documentation

On 06/21/2016 05:28 PM, Jacek Anaszewski wrote:
> Hi Florian,
>
> Thanks for the patch. I have two remarks below.
>
> On 06/21/2016 09:29 AM, Florian Vaussard wrote:
>> Add device tree binding documentation for On Semiconductor NCP5623 I2C
>> LED driver. The driver can independently control the PWM of the 3
>> channels with 32 levels of intensity.
>>
>> The current delivered by the current source can be controlled using the
>> led-max-microamp property. In order to control this value, it is also
>> necessary to know the current on the Iref pin, hence the
>> onnn,led-iref-microamp property. It is usually set using an external
>> bias resistor, following Iref = Vref/Rbias with Vref=0.6V.
>>
>> Signed-off-by: Florian Vaussard <florian.vaussard@...g-vd.ch>
>> ---
>>   .../devicetree/bindings/leds/leds-ncp5623.txt      | 44
>> ++++++++++++++++++++++
>>   1 file changed, 44 insertions(+)
>>   create mode 100644
>> Documentation/devicetree/bindings/leds/leds-ncp5623.txt
>>
>> diff --git a/Documentation/devicetree/bindings/leds/leds-ncp5623.txt
>> b/Documentation/devicetree/bindings/leds/leds-ncp5623.txt
>> new file mode 100644
>> index 0000000..0dc8345
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/leds/leds-ncp5623.txt
>> @@ -0,0 +1,44 @@
>> +* ON Semiconductor - NCP5623 3-Channel LED Driver
>> +
>> +The NCP5623 is a 3-channel I2C LED driver. The brightness of each
>> +channel can be independently set using 32 levels. Each LED is
>> represented
>> +as a sub-node of the device.
>> +
>> +Required properties:
>> +  - compatible: Should be "onnn,ncp5623"
>> +  - reg: I2C slave address (fixed to 0x38)
>> +  - #address-cells: must be 1
>> +  - #size-cells: must be 0
>> +  - onnn,led-iref-microamp: Current on the Iref pin in microampere
>
> I think that you don't need this property. Just provide the formula for
> calculating led-max-microamp value, similarly as you're doing that in
> the commit message.
>
>> +  - led-max-microamp: Desired maximum current for each LED in
>> microampere
>> +                      (maximum 30000uA)
>
> Please add instead of (maximum ...):
>
> Valid values: min - max, step by N (rounded {up|down})
>
> E.g.
>
> Valid values: 10000 - 30000, step by 1000 (rounded down)
>
>> +
>> +LED sub-node properties:
>> +  - reg : LED channel number (0..2)
>> +  - For other LED properties see:
>> +      Documentation/devicetree/bindings/leds/common.txt
>> +
>> +Example:
>> +
>> +led1: ncp5623@38 {
>> +    #address-cells = <1>;
>> +    #size-cells = <0>;
>> +    compatible = "onnn,ncp5623";
>> +    reg = <0x38>;
>> +
>> +    led1_r@0 {
>> +        label = "ncp:power:red";
>> +        reg = <0>;
>> +        linux,default-trigger = "default-on";

Please add also led-max-microamp to all child nodes in this example.

>> +    };
>> +
>> +    led1_b@1 {
>> +        label = "ncp:power:blue";
>> +        reg = <1>;
>> +    };
>> +
>> +    led1_g@2 {
>> +        label = "ncp:power:green";
>> +        reg = <2>;
>> +    };
>> +};
>>
>
>


-- 
Best regards,
Jacek Anaszewski