Re: [PATCH v19 04/18] leds: multicolor: Introduce a multicolor class definition

[Dan Murphy]

Randy

Thanks for the review

On 4/2/20 10:47 PM, Randy Dunlap wrote:
> Hi,
> Here are a few changes for you to consider:
>
> On 4/2/20 1:42 PM, Dan Murphy wrote:
> > Introduce a multicolor class that groups colored LEDs
> > within a LED node.
> >
> > The multi color class groups monochrome LEDs and allows controlling two
>        multicolor
Ack
> > aspects of the final combined color: hue and lightness. The former is
> > controlled via <color>_intensity files and the latter is controlled
> > via brightness file.
> >
> > Signed-off-by: Dan Murphy <dmurphy@xxxxxx>
> > ---
>
> > diff --git a/Documentation/leds/leds-class-multicolor.rst b/Documentation/leds/leds-class-multicolor.rst
> > new file mode 100644
> > index 000000000000..5bb004999248
> > --- /dev/null
> > +++ b/Documentation/leds/leds-class-multicolor.rst
> > @@ -0,0 +1,95 @@
> > +====================================
> > +Multi Color LED handling under Linux
>     Multicolor
Ack
> > +====================================
> > +
> > +Description
> > +===========
> > +The multi color class groups monochrome LEDs and allows controlling two
>         multicolor
Ack
> > +aspects of the final combined color: hue and lightness. The former is
> > +controlled via the color_intensity array file and the latter is controlled
> > +via brightness file.
> > +
> > +For more details on hue and lightness notions please refer to
> > +https://en.wikipedia.org/wiki/CIECAM02.
> > +
> > +Multicolor Class Control
> > +========================
> > +The multicolor class presents files that groups the colors as indexes in an
> > +array.  These files are children under the LED parent node created by the
> > +led_class framework.  The led_class framework is documented in led-class.rst
> > +within this documentation directory.
> > +
> > +Each colored LED will be indexed under the color_* files. The order of the
> > +colors are arbitrary the color_index file can be read to determine the color
> > +to index value.
> > +
> > +The color_index file is an array that contains the string list of the colors as
> > +they are defined in each color_* array file.
> > +
> > +The color_intensity is an array that can be read or written to for the
> > +individual color intensities.  All elements within this array must be written in
> > +order for the color LED intensities to be updated.
> > +
> > +The color_max_intensity is an array that can be read to indicate each color LED
> > +maximum intensity value.
> > +
> > +The num_color_leds file returns the total number of color LEDs that are
> > +presented in each color_* array.
> > +
> > +Directory Layout Example
> > +========================
> > +root:/sys/class/leds/multicolor:status# ls -lR
> > +-rw-r--r--    1 root     root          4096 Oct 19 16:16 brightness
> > +-r--r--r--    1 root     root          4096 Oct 19 16:16 color_index
> > +-rw-r--r--    1 root     root          4096 Oct 19 16:16 color_intensity
> > +-r--r--r--    1 root     root          4096 Oct 19 16:16 num_color_leds
> > +
> > +Multicolor Class Brightness Control
> > +===================================
> > +The multiclor class framework will calculate each monochrome LEDs intensity.
>         multicolor
Ack
> > +
> > +The brightness level for each LED is calculated based on the color LED
> > +intensity setting divided by the parent max_brightness setting multiplied by
> > +the requested brightness.
> > +
> > +led_brightness = brightness * color_intensity/max_brightness
> > +
> > +Example:
> > +A user first writes the color_intensity file with the brightness levels
> > +that for each LED that is necessary to achieve a blueish violet output from a
> drop first "that".
Ack
>                       that are necessary                                   from an
Ack and NACK the "from an". It is from a since R is a consonant
> > +RGB LED group.
> > +
> > +cat /sys/class/leds/multicolor:status/color_index
> > +green blue red
> > +
> > +echo 43 226 138 > /sys/class/leds/multicolor:status/color_intensity
> > +
> > +red -
> > +	intensity = 138
> > +	max_brightness = 255
> > +green -
> > +	intensity = 43
> > +	max_brightness = 255
> > +blue -
> > +	intensity = 226
> > +	max_brightness = 255
> > +
> > +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
>                  value.
Ack
> > +
> > +cat /sys/class/leds/multicolor:status/max_brightness
> > +255
> > +echo 128 > /sys/class/leds/multicolor:status/brightness
> > +
> > +adjusted_red_value = 128 * 138/255 = 69
> > +adjusted_green_value = 128 * 43/255 = 21
> > +adjusted_blue_value = 128 * 226/255 = 113
> > +
> > +Reading the parent brightness file will return the current brightness value of
> > +the color LED group.
> > +
> > +cat /sys/class/leds/multicolor:status/brightness
> > +128
> > diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> > index d82f1dea3711..2e4611b25054 100644
> > --- a/drivers/leds/Kconfig
> > +++ b/drivers/leds/Kconfig
> > @@ -30,6 +30,16 @@ config LEDS_CLASS_FLASH
> >   	  for the flash related features of a LED device. It can be built
> >   	  as a module.
> >   
> > +config LEDS_CLASS_MULTI_COLOR
> > +	tristate "LED Multi Color LED Class Support"
> 	              Multicolor

Ack

Dan