linux-kernel - Re: [PATCH v3 1/2] dt-bindings: leds: Add bindings for lm3697 driver

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Date:   Wed, 15 Aug 2018 12:30:22 -0500
From:   Dan Murphy <dmurphy@...com>
To:     Jacek Anaszewski <jacek.anaszewski@...il.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 v3 1/2] dt-bindings: leds: Add bindings for lm3697 driver

Jacek

On 08/15/2018 11:56 AM, Jacek Anaszewski wrote:
> Hi Dan,
> 
> Thank you for the update.
> 
> On 08/15/2018 06:17 PM, Dan Murphy wrote:
>> Add the device tree bindings for the lm3697
>> LED driver for backlighting and display.
>>
>> Signed-off-by: Dan Murphy <dmurphy@...com>
>> ---
>>
>> v3 - Updated subject with prefered title - https://lore.kernel.org/patchwork/patch/972337/
>> v2 - Fixed subject and patch commit message - https://lore.kernel.org/patchwork/patch/971326/
>>
>>  .../devicetree/bindings/leds/leds-lm3697.txt  | 89 +++++++++++++++++++
>>  1 file changed, 89 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/leds/leds-lm3697.txt
>>
>> diff --git a/Documentation/devicetree/bindings/leds/leds-lm3697.txt b/Documentation/devicetree/bindings/leds/leds-lm3697.txt
>> new file mode 100644
>> index 000000000000..34403a48a0ce
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/leds/leds-lm3697.txt
>> @@ -0,0 +1,89 @@
>> +* Texas Instruments - LM3697 Highly Efficient White LED Driver
>> +
>> +The LM3697 11-bit LED driver provides high-
>> +performance backlight dimming for 1, 2, or 3 series
>> +LED strings while delivering up to 90% efficiency.
>> +
>> +This device is suitable for Display and Keypad Lighting
>> +
>> +Required properties:
>> +	- compatible:
>> +		"ti,lm3967"
>> +	- 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 : 0 - LED is Controlled by bank A
>> +		1 - LED is Controlled by bank B
>> +	- led-sources - Indicates which HVLED string is associated to which
>> +			control bank.  The HVLED string cannot be associated with
>> +			two control banks.  This property is an array of 3 and
>> +			all positions in the array must be populated.
>> +			Additional information is contained
>> +			in Documentation/devicetree/bindings/leds/common.txt
>> +			0 - End of array if all 3 LEDs are not declared for a
>> +			    single control bank.
> 
> This is needless complication. I propose to define led-sources as
> an array of three boolean values, whose state signifies which LED
> strings are controlled by the bank defined by the reg property in the
> given child node. I.e. <HVLED1 HVLED2 HVLED3>.

I struggled a bit with this definition.  Once I got it working it ended up producing
an overly complex control bank algorithm.

I will take a look at implementing the suggestion but the complication comes in the
numerous DT configurations we could encounter.  Part of the issue is that the user
can connect to CTRL bank b only or CTRL bank a only or a combination of that

2^3

Dan

> 
> I modified your examples below accordingly.
> 
>> +			1 - HVLED 1 string
>> +			2 - HVLED 2 string
>> +			3 - HVLED 3 string
>> +
>> +Optional child properties:
>> +	- label : see Documentation/devicetree/bindings/leds/common.txt
>> +	- linux,default-trigger :
>> +	   see Documentation/devicetree/bindings/leds/common.txt
>> +
>> +Example:
>> +
>> +HVLED string 1 and 2 controlled by control bank A and HVLED string controlled by
>> +control bank B.
>> +
>> +led-controller@36 {
>> +	compatible = "ti,lm3967";
>> +	reg = <0x36>;
>> +	#address-cells = <1>;
>> +	#size-cells = <0>;
>> +
>> +	enable-gpios = <&gpio1 28 GPIO_ACTIVE_HIGH>;
>> +	vled-supply = <&vbatt>;
>> +
>> +	led@0 {
>> +		reg = <0>;
>> +		led-sources = <0x1 0x2 0x0>
> 
> 		led-sources = <1 1 0>;
> ;
>> +		label = "white:first_backlight_cluster";
>> +		linux,default-trigger = "backlight";
>> +	};
>> +
>> +	led@1 {
>> +		reg = <1>;
>> +		led-sources = <0x3 0x0 0x0>;
> 
> 		led-sources = <0 0 1>;
> 
>> +		label = "white:second_backlight_cluster";
>> +		linux,default-trigger = "backlight";
>> +	};
>> +}
>> +
>> +All HVLED strings controlled by control bank A
>> +
>> +led-controller@36 {
>> +	compatible = "ti,lm3967";
>> +	reg = <0x36>;
>> +	#address-cells = <1>;
>> +	#size-cells = <0>;
>> +
>> +	enable-gpios = <&gpio1 28 GPIO_ACTIVE_HIGH>;
>> +	vled-supply = <&vbatt>;
>> +
>> +	led@0 {
>> +		reg = <0>;
>> +		led-sources = <0x1 0x2 0x3>;
> 
> 		led-sources = <1 1 1>;
> 
>> +		label = "white:backlight_cluster";
>> +		linux,default-trigger = "backlight";
>> +	};
>> +}
>> +
>> +For more product information please see the link below:
>> +http://www.ti.com/lit/ds/symlink/lm3697.pdf
>>
> 


-- 
------------------
Dan Murphy