Date:   Tue, 27 Aug 2019 11:54:22 -0500
From:   Dan Murphy <dmurphy@...com>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>, <pavel@....cz>
CC:     <linux-leds@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/9] leds: multicolor: Add sysfs interface definition

Jacek

OK finally getting back to this.

On 7/29/19 3:45 PM, Jacek Anaszewski wrote:
> Hi Dan,
>
> Thank you for the v4.
>
> I have a bunch of comments below. Please take a look.
>
> On 7/25/19 8:28 PM, Dan Murphy wrote:
>> Add a documentation of LED Multicolor LED class specific
>> sysfs attributes.
>>
>> Signed-off-by: Dan Murphy<dmurphy@...com>
>> ---
>>   .../ABI/testing/sysfs-class-led-multicolor    | 67 +++++++++++++++++++
>>   1 file changed, 67 insertions(+)
>>   create mode 100644 Documentation/ABI/testing/sysfs-class-led-multicolor
>>
>> diff --git a/Documentation/ABI/testing/sysfs-class-led-multicolor b/Documentation/ABI/testing/sysfs-class-led-multicolor
>> new file mode 100644
>> index 000000000000..59839f0eae76
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-class-led-multicolor
>> @@ -0,0 +1,67 @@
>> +What:		/sys/class/leds/<led>/brightness
>> +Date:		Sept 2019
>> +KernelVersion:	TBD
>> +Contact:	Dan Murphy<dmurphy@...com>
>> +Description:	read/write
>> +		The multicolor class will redirect the device drivers call back
>> +		function for brightness control to the multicolor class
>> +		brightness control function.
>> +
>> +		Writing to this file will update all LEDs within the group to a
>> +		calculated percentage of what each color LED in the group is set
>> +		to.  Please refer to the leds-class-multicolor.txt in the
>> +		Documentation directory for a complete description.
> Instead of redirecting the reader to led-class-multicolor.txt I'd prefer
> to have at least the formula to calculate the colors laid out here.
> Aside of that - it is more helpful to have a full path to the referenced
> file.

Ack


>> +
>> +		The value of the color is from 0 to
>> +		/sys/class/leds/<led>/max_brightness.
>> +
>> +What:		/sys/class/leds/<led>/colors/color_mix
>> +Date:		Sept 2019
>> +KernelVersion:	TBD
>> +Contact:	Dan Murphy<dmurphy@...com>
>> +Description:	read/write
>> +		The color_mix file allows writing all registered multicolor LEDs
>> +		virtually at the same time.  The value(s) written to this file
> I'd drop parentheses form "value(s)". Multi color LED class device is
> supposed to always have more then one LED. And if I understand it
> correctly we have to pass intensities of all colors supported by LED
> multicolor class device here, even we're changing single one.

Yes that is true.


>> +		contain the intensity values for each multicolor LED within
>> +		the colors directory.  The color indexes are reported in the
>> +		color_id file as defined in this document.
> This is a bit misleading. It sounds as if single color_id file would be
> reporting more than one index.
>
>> +		Please refer to the leds-class-multicolor.txt in the
>> +		Documentation directory for a complete description.
> Here, similarly as for brightness, I would prefer to have complete
> documentation of this file.
>
> How about:
>
> The values written to this file should contain the intensity values of
> each multicolor LED within the colors directory. The index of given
> color is reported by the color_id file present in colors/<color>
> directory. The index determines the position in the sequence of
> intensities on which the related intensity should be passed to this
> file.
>
> And here we could have the examples from leds-class-multicolor.txt.

I prefer to keep the examples in the leds-class-multicolor.rst.

This is an ABI document not a document describing the code.

I updated the doc to what you have above.

>> +
>> +What:		/sys/class/leds/<led>/colors/<led_color>/color_id
>> +Date:		Sept 2019
>> +KernelVersion:	TBD
>> +Contact:	Dan Murphy<dmurphy@...com>
>> +Description:	read only
>> +		This file when read will return the index of the color in the
>> +		color_mix.
>> +		Please refer to the leds-class-multicolor.txt in the
>> +		Documentation directory for a complete description.
>> +
>> +What:		/sys/class/leds/<led>/colors/<led_color>/intensity
>> +Date:		Sept 2019
>> +KernelVersion:	TBD
>> +Contact:	Dan Murphy<dmurphy@...com>
>> +Description:	read/write
>> +		The led_color directory is dynamically created based on the
>> +		colors defined by the registrar of the class.
>> +		The led_color can be but not limited to red, green, blue,
>> +		white, amber, yellow and violet.  Drivers can also declare a
> Instead of this vague sentence about the available colors I propose to
> maintain the list of supported colors in leds-class.rst or in a separate
> file and keep it in sync with the led_colors array. Then we could refer
> to that file here.

I would rather point to the file that contains the colors.  This way we 
don't have added documentation

maintenance to add a new color.


>
>> +		LED color for presentation.  There is one directory per color
> I'd not let drivers define their custom colors. It would entail issues
> related to lack of generic LED_COLOR_ID and DT parsing failure.

Ack

Dan

>
>> +		presented.  The brightness file is created under each
>> +		led_color directory and controls the individual LED color
>> +		setting.
>> +
>> +		The value of the color is from 0 to
>> +		/sys/class/leds/<led>/colors/<led_color>/max_intensity.
>> +
>> +What:		/sys/class/leds/<led>/colors/<led_color>/max_intensity
>> +Date:		Sept 2019
>> +KernelVersion:	TBD
>> +Contact:	Dan Murphy<dmurphy@...com>
>> +Description:	read only
>> +		Maximum intensity level for the LED color, default is
>> +		255 (LED_FULL).
>> +
>> +		If the LED does not support different intensity levels, this
>> +		should be 1.
>>

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