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

[Jacek Anaszewski]

Dan,

On 08/15/2018 07:30 PM, Dan Murphy wrote:
> 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@xxxxxx>
>>> ---
>>>
>>> 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

I tried to play a bit with that and here is what I got (simplified
DT parsing):

int used_hvleds[3] = {0, 0 ,0};
int used_control_banks[2] = {0, 0};

int parse_child_node(struct fwnode_handle *child)
{
	int bank_hvleds[3];

	fwnode_property_read_u32_array(child, "led-sources",
		bank_hvleds, LM3697_MAX_LED_STRINGS);

	for (i = 0; i <= 3; i++) {
		if (bank_hvleds[i] && used_hvleds[i])
			return -EINVAL;
		used_hvleds[i] = 1;
	}

	return 0;
}

struct fwnode_handle *child = NULL;

device_for_each_child_node(priv->dev, child)
	fwnode_property_read_u32(child, "reg", &control_bank);
	if (used_control_banks[control_bank])
		goto err;
	used_control_banks[control_bank] = 1;
	if (parse_child_node(child))
		goto err;


>>
>> 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
>>>
>>
> 
> 

-- 
Best regards,
Jacek Anaszewski