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

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Date:   Wed, 29 Mar 2017 16:26:13 +0200
From:   Felix Brack <fb@...c.ch>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>, riku.voipio@....fi,
        rpurdie@...ys.net, pavel@....cz, linux-leds@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     f.brack@...s.ch
Subject: Re: [PATCH] leds: pca9532: Extend pca9532 device tree support

Hello Jacek,

On 08.02.2017 20:42, Jacek Anaszewski wrote:
> Hi Felix,
> 
> On 02/08/2017 05:12 PM, Felix Brack wrote:
>> Hello Jacek,
>>
>> On 07.02.2017 21:45, Jacek Anaszewski wrote:
>>> Hi Felix,
>>>
>>> Thanks for the patch.
>>>
>>> On 02/07/2017 07:11 PM, Felix Brack wrote:
>>>> This patch extends the device tree support for the pca9532 allowing LEDs to blink, dim or even being unchanged, i.e. not being turned off during driver initialization.
>>>
>>> Isn't it possible to apply desired settings with existing LED subsystem
>>> brightness file, and delay_on/off files exposed by timer trigger?
>>>
>>> Best regards,
>>> Jacek Anaszewski
>>>
>>
>> This might be a misunderstanding. My patch is not meant to replace
>> anything for driving the LEDs once the kernel is fully loaded. The LED
>> subsystem offers quite a lot of possibilities to do this.
>>
>> My patch mainly deals with the 'default' state of the LEDs immediately
>> when the driver gets loaded.
>> Here is an example: I have a system with a LED named 'RUN' which is
>> turned on steady by U-Boot (indicating "system booting"). When the
>> PCA9532 driver loads this LED gets turned off due to initialization.
>> However I would like it remain lit until later a script will make that
>> 'RUN' LED blink (indicating "system running"). This script will of
>> course use the existing LED subsystem to do so. To keep the 'RUN' LED
>> lit I need the DT property 'default-state' being set to 'PCA9532_KEEP'.
> 
> It looks like all you need is default-state property.
> I'd rather avoid exposing prescaler and pwm registers in DT.
> 

For the time being there seems to be no generic timer configuration by
means of the DT. I have therefore decided to remove the code dealing
with prescaler and pwm from my patch. This will prevent those registers
from being exposed to the DT. What will remain is the default-state.

Should I send an updated version (v2) of this patch or would it be
better to send a 'new' patch?

regards, Felix