linux-kernel - Re: [PATCH v2] Extend pca9532 device tree support

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Date:   Thu, 6 Apr 2017 21:00:09 +0200
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Pavel Machek <pavel@....cz>, Felix Brack <fb@...c.ch>
Cc:     rpurdie@...ys.net, mark.rutland@....com, riku.voipio@....fi,
        linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] Extend pca9532 device tree support

Hi Pavel,

On 04/06/2017 05:50 PM, Pavel Machek wrote:
> Hi!
> 
>>> diff --git a/Documentation/devicetree/bindings/leds/leds-pca9532.txt b/Documentation/devicetree/bindings/leds/leds-pca9532.txt
>>> index 198f3ba..8374075 100644
>>> --- a/Documentation/devicetree/bindings/leds/leds-pca9532.txt
>>> +++ b/Documentation/devicetree/bindings/leds/leds-pca9532.txt
>>> @@ -17,6 +17,8 @@ Optional sub-node properties:
>>>  	- label: see Documentation/devicetree/bindings/leds/common.txt
>>>  	- type: Output configuration, see dt-bindings/leds/leds-pca9532.h (default NONE)
>>>  	- linux,default-trigger: see Documentation/devicetree/bindings/leds/common.txt
>>> +	- default-state: see Documentation/devicetree/bindings/leds/common.txt
>>> +	  This property is only valid for sub-nodes of type <PCA9532_TYPE_LED>.
>>>  
>>>  Example:
>>>    #include <dt-bindings/leds/leds-pca9532.h>
>>> @@ -33,6 +35,14 @@ Example:
>>>        label = "pca:green:power";
>>>        type = <PCA9532_TYPE_LED>;
>>>      };
>>> +    kernel-booting {
>>> +    	type = <PCA9532_TYPE_LED>;
>>> +    	default-state = "on";
>>> +    };
>>> +    sys-stat {
>>> +    	type = <PCA9532_TYPE_LED>;
>>> +    	default-state = "keep"; // don't touch, was set by U-Boot
>>> +    };
>>
>> Adjusted above indentation to match the preceding lines.
> 
>>> @@ -475,6 +494,16 @@ pca9532_of_populate_pdata(struct device *dev, struct device_node *np)
>>>  		of_property_read_u32(child, "type", &pdata->leds[i].type);
>>>  		of_property_read_string(child, "linux,default-trigger",
>>>  					&pdata->leds[i].default_trigger);
>>> +		if (!of_property_read_string(child, "default-state", &state)) {
>>> +			if (!strcmp(state, "on"))
>>> +				pdata->leds[i].state = PCA9532_ON;
>>> +			else if (!strcmp(state, "keep"))
>>> +				pdata->leds[i].state = PCA9532_KEEP;
>>> +			else if (!strcmp(state, "pwm0"))
>>> +				pdata->leds[i].state = PCA9532_PWM0;
>>> +			else if (!strcmp(state, "pwm1"))
>>> +				pdata->leds[i].state = PCA9532_PWM1;
>>> +		}
>>>  		if (++i >= maxleds) {
>>>  			of_node_put(child);
>>>  			break;
> 
> This seems to look for "pwm0" and "pwm1" strings, which do not seem to
> be documented.
> 
> Plus... is it useful to have default-state? We already have default
> trigger. If we keep the value by default (on PC, we do something like
> that) this patch should not be neccessary?

Thanks for the heads-up. Dropping the patch for now.
I guess that pwm0/1 got propagated to v2 by an omission.

Regarding default-on: Felix, do you have any use case that require
default-on set to "keep"?

-- 
Best regards,
Jacek Anaszewski