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Documentation: leds: improve readibility of multicolor doc

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When reading the documentation of multicolor leds, the HTML output is
not easy to read. Improve it by adding a few markups, splitting the
console in a dedicated block.

Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@yoseli.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20250421-leds-doc-v1-1-9a32df7fc6f4@yoseli.org>
This commit is contained in:
Jean-Michel Hautbois
2025-04-21 18:48:10 +02:00
committed by Jonathan Corbet
parent 8f82b560c5
commit 422f5b78bf
1 changed files with 51 additions and 31 deletions
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82
Documentation/leds/leds-class-multicolor.rst
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@@ -18,24 +18,28 @@ 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 led_class framework. The led_class framework is documented in led-class.rst
within this documentation directory. within this documentation directory.
Each colored LED will be indexed under the multi_* files. The order of the Each colored LED will be indexed under the ``multi_*`` files. The order of the
colors will be arbitrary. The multi_index file can be read to determine the colors will be arbitrary. The ``multi_index`` file can be read to determine the
color name to indexed value. color name to indexed value.
The multi_index file is an array that contains the string list of the colors as The ``multi_index`` file is an array that contains the string list of the colors as
they are defined in each multi_* array file. they are defined in each ``multi_*`` array file.
The multi_intensity is an array that can be read or written to for the The ``multi_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 individual color intensities. All elements within this array must be written in
order for the color LED intensities to be updated. order for the color LED intensities to be updated.
Directory Layout Example Directory Layout Example
======================== ========================
root:/sys/class/leds/multicolor:status# ls -lR .. code-block:: console
-rw-r--r-- 1 root root 4096 Oct 19 16:16 brightness
-r--r--r-- 1 root root 4096 Oct 19 16:16 max_brightness root:/sys/class/leds/multicolor:status# ls -lR
-r--r--r-- 1 root root 4096 Oct 19 16:16 multi_index -rw-r--r-- 1 root root 4096 Oct 19 16:16 brightness
-rw-r--r-- 1 root root 4096 Oct 19 16:16 multi_intensity -r--r--r-- 1 root root 4096 Oct 19 16:16 max_brightness
-r--r--r-- 1 root root 4096 Oct 19 16:16 multi_index
-rw-r--r-- 1 root root 4096 Oct 19 16:16 multi_intensity
..
Multicolor Class Brightness Control Multicolor Class Brightness Control
=================================== ===================================
@@ -43,27 +47,31 @@ The brightness level for each LED is calculated based on the color LED
intensity setting divided by the global max_brightness setting multiplied by intensity setting divided by the global max_brightness setting multiplied by
the requested brightness. the requested brightness.
led_brightness = brightness * multi_intensity/max_brightness ``led_brightness = brightness * multi_intensity/max_brightness``
Example: Example:
A user first writes the multi_intensity file with the brightness levels A user first writes the multi_intensity file with the brightness levels
for each LED that are necessary to achieve a certain color output from a for each LED that are necessary to achieve a certain color output from a
multicolor LED group. multicolor LED group.
cat /sys/class/leds/multicolor:status/multi_index .. code-block:: console
green blue red
echo 43 226 138 > /sys/class/leds/multicolor:status/multi_intensity # cat /sys/class/leds/multicolor:status/multi_index
green blue red
red - # echo 43 226 138 > /sys/class/leds/multicolor:status/multi_intensity
intensity = 138
max_brightness = 255 red -
green - intensity = 138
intensity = 43 max_brightness = 255
max_brightness = 255 green -
blue - intensity = 43
intensity = 226 max_brightness = 255
max_brightness = 255 blue -
intensity = 226
max_brightness = 255
..
The user can control the brightness of that multicolor LED group by writing the The user can control the brightness of that multicolor LED group by writing the
global 'brightness' control. Assuming a max_brightness of 255 the user global 'brightness' control. Assuming a max_brightness of 255 the user
@@ -71,16 +79,28 @@ may want to dim the LED color group to half. The user would write a value of
128 to the global brightness file then the values written to each LED will be 128 to the global brightness file then the values written to each LED will be
adjusted base on this value. adjusted base on this value.
cat /sys/class/leds/multicolor:status/max_brightness .. code-block:: console
255
echo 128 > /sys/class/leds/multicolor:status/brightness
adjusted_red_value = 128 * 138/255 = 69 # cat /sys/class/leds/multicolor:status/max_brightness
adjusted_green_value = 128 * 43/255 = 21 255
adjusted_blue_value = 128 * 226/255 = 113 # echo 128 > /sys/class/leds/multicolor:status/brightness
..
.. code-block:: none
adjusted_red_value = 128 * 138/255 = 69
adjusted_green_value = 128 * 43/255 = 21
adjusted_blue_value = 128 * 226/255 = 113
..
Reading the global brightness file will return the current brightness value of Reading the global brightness file will return the current brightness value of
the color LED group. the color LED group.
cat /sys/class/leds/multicolor:status/brightness .. code-block:: console
128
# cat /sys/class/leds/multicolor:status/brightness
128
..