linux-kernel - Re: [PATCH v5 2/2] documention: leds: Add multicolor class documentation

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Message-ID: <6e5daa02-f507-e329-cc56-465954d0996b@gmail.com>
Date:   Tue, 16 Jul 2019 22:37:40 +0200
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Dan Murphy <dmurphy@...com>, pavel@....cz
Cc:     linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 2/2] documention: leds: Add multicolor class
 documentation

Dan,

On 7/16/19 9:27 PM, Dan Murphy wrote:
> Jacek
> 
> On 7/16/19 2:18 PM, Jacek Anaszewski wrote:
>> Hi Dan,
>>
>> Thanks for the update. I have some nits below, please take a look.
>>
>> On 7/1/19 10:46 PM, Dan Murphy wrote:
[...]

>>> +The user can control the brightness of that RGB group by writing the
>>> parent
>>> +'brightness' control.  Assuming a parent max_brightness of 255 the
>>> user may want
>>> +to dim the LED color group to half.  The user would write a value of
>>> 128 to the
>>> +parent brightness file then the values written to each LED will be
>>> adjusted
>>> +base on this value
>> We probably need to state here that any amendment to color intensity
>> values resets brightness to its max value.
> 
> Well that is not true.  Intensity and brightness are two different spaces.

OK, I had to go through the sequence of steps I had on mind.
I had to work it out that colors set under colors directory don't
reflect the iout colors, but are only used for calculating them,
basing on the brightness and max_intensity values.

Effectively, after changing the colors/<color>/intensity the brightness
value will be still valid, since iout color will be recalculated basing
on the currently set brightness and the new color intensity.

> Brightness is for cluster control and intensity is for monochrome LED
> control.
> 
> There only relationship is when setting cluster brightness.


-- 
Best regards,
Jacek Anaszewski