linux-kernel - Re: [PATCH 1/2] dt: bindings: lp5024: Introduce the lp5024 and lp5018 RGB driver

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Date:   Tue, 8 Jan 2019 22:16:48 +0100
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Dan Murphy <dmurphy@...com>, robh+dt@...nel.org, pavel@....cz
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-leds@...r.kernel.org
Subject: Re: [PATCH 1/2] dt: bindings: lp5024: Introduce the lp5024 and lp5018
 RGB driver

On 1/8/19 9:53 PM, Dan Murphy wrote:
> Jacek
> 
> On 1/8/19 2:33 PM, Jacek Anaszewski wrote:
>> Dan,
>>
>> On 12/19/18 5:26 PM, Dan Murphy wrote:
>>> Introduce the bindings for the Texas Instruments LP5024 and the LP5018
>>> RGB LED device driver.  The LP5024/18 can control RGB LEDs individually
>>> or as part of a control bank group.  These devices have the ability
>>> to adjust the mixing control for the RGB LEDs to obtain different colors
>>> independent of the overall brightness of the LED grouping.
>>>
>>> Datasheet:
>>> http://www.ti.com/lit/ds/symlink/lp5024.pdf
>>>
>>> Signed-off-by: Dan Murphy <dmurphy@...com>
>>> ---
>>>    .../devicetree/bindings/leds/leds-lp5024.txt  | 63 +++++++++++++++++++
>>>    1 file changed, 63 insertions(+)
>>>    create mode 100644 Documentation/devicetree/bindings/leds/leds-lp5024.txt
>>>
>>> diff --git a/Documentation/devicetree/bindings/leds/leds-lp5024.txt b/Documentation/devicetree/bindings/leds/leds-lp5024.txt
>>> new file mode 100644
>>> index 000000000000..9567aa6f7813
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/leds/leds-lp5024.txt
>>> @@ -0,0 +1,63 @@
>>> +* Texas Instruments - LP5024/18 RGB LED driver
>>> +
>>> +The LM3692x is an ultra-compact, highly efficient,
>>> +white-LED driver designed for LCD display backlighting.
>>> +
>>> +The main difference between the LP5024 and L5018 is the number of
>>> +RGB LEDs they support.  The LP5024 supports twenty four strings while the
>>> +LP5018 supports eighteen strings.
>>> +
>>> +Required properties:
>>> +    - compatible:
>>> +        "ti,lp5018"
>>> +        "ti,lp5024"
>>> +    - reg :  I2C slave address
>>> +    - #address-cells : 1
>>> +    - #size-cells : 0
>>> +
>>> +Optional properties:
>>> +    - enable-gpios : gpio pin to enable/disable the device.
>>> +    - vled-supply : LED supply
>>> +
>>> +Required child properties:
>>> +    - reg : Is the child node iteration.
>>> +    - led-sources : LP5024 - 0 - 7
>>> +            LP5018 - 0 - 5
>>> +            Declares the LED string or strings that the child node
>>> +            will control.  If ti,control-bank is set then this
>>> +            property will contain multiple LED IDs.
>>> +
>>> +Optional child properties:
>>> +    - label : see Documentation/devicetree/bindings/leds/common.txt
>>> +    - linux,default-trigger :
>>> +       see Documentation/devicetree/bindings/leds/common.txt
>>> +    - ti,control-bank : Indicates that the LED strings declared in the
>>> +                led-sources property are grouped within a control
>>> +                bank for brightness and mixing control.
>>> +
>>> +Example:
>>> +
>>> +led-controller@28 {
>>> +    compatible = "ti,lp5024";
>>> +    reg = <0x28>;
>>> +    #address-cells = <1>;
>>> +    #size-cells = <0>;
>>> +
>>> +    enable-gpios = <&gpio1 28 GPIO_ACTIVE_HIGH>;
>>> +    vled-supply = <&vbatt>;
>>> +
>>> +    led@0 {
>>> +        reg = <0>;
>>> +        led-sources = <1>;
>>> +    };
>>> +
>>> +    led@1 {
>>> +        reg = <1>;
>>> +        led-sources = <0 6>;
>>> +        ti,control-bank;
>>
>> Do you really need ti,control-bank? Doesn't led-sources array size
>> greater than 1 mean that the node describes control bank?
>>
> 
> That will work too.

>> Also, does it make sense to have only two LEDs in the bank?
> 
> The array can populate all 7 LEDs in a single node.  I only show 2 here as the example.
> See the description above of the led-sources

OK, I confused RGB LED modules with banks.

Shouldn't we allow for defining either strings or RGB LED
triplets somehow then?

-- 
Best regards,
Jacek Anaszewski