[CH23]

@NiLuJe

I don't know if you've heard about the backlight issue on the Clara yet, (probably not as I don't think anybody else has got KOReader running on that?) but I got the following error message, which might interest you:

                launching...
  _  _____  ____                _
 | |/ / _ \|  _ \ ___  __ _  __| | ___ _ __
 | ' / | | | |_) / _ \/ _` |/ _` |/ _ \ '__|
 | . \ |_| |  _ <  __/ (_| | (_| |  __/ |
 |_|\_\___/|_| \_\___|\__,_|\__,_|\___|_|

 It's a scroll... It's a codex... It's KOReader!
[*] Current time: 07/19/18-10:10:24[*] Version: v2015.11-1735-g14e7730_2018-06-02

[...]

07/19/18-10:10:24 ERROR Could not open file:  /sys/class/backlight/lm3630a_led1b/bl_power
07/19/18-10:10:24 ERROR Could not open file:  /sys/class/backlight/lm3630a_led1b/brightness
07/19/18-10:10:24 ERROR Could not open file:  /sys/class/backlight/lm3630a_led1a/bl_power
07/19/18-10:10:24 ERROR Could not open file:  /sys/class/backlight/lm3630a_led1a/brightness
07/19/18-10:10:24 INFO  initializing for device Kobo_nova

[...]

this is a snippet of crash.log

doing

ls -lah /sys/class/backlight/

(from KSM web interface) gives the following:

 ### executed:ls -lah /sys/class/backlight/

total 0
drwxr-xr-x    2 root     root           0 Jul 19 21:15 .
drwxr-xr-x   38 root     root           0 Jul 19 21:06 ..
lrwxrwxrwx    1 root     root           0 Jul 19 21:15 lm3630a_led -> ../../devices/platform/soc/2100000.aips-bus/21a0000.i2c/i2c-0/0-0036/backlight/lm3630a_led
lrwxrwxrwx    1 root     root           0 Jul 19 21:15 lm3630a_leda -> ../../devices/platform/soc/2100000.aips-bus/21a0000.i2c/i2c-0/0-0036/backlight/lm3630a_leda
lrwxrwxrwx    1 root     root           0 Jul 19 21:15 lm3630a_ledb -> ../../devices/platform/soc/2100000.aips-bus/21a0000.i2c/i2c-0/0-0036/backlight/lm3630a_ledb
lrwxrwxrwx    1 root     root           0 Jul 19 21:15 mxc_msp430.0 -> ../../devices/platform/ntx_bl/backlight/mxc_msp430.0

the names don't match:
koreader wants led1a. led1b
the filesystem has leda, ledb

led controls orange and white (values 0 - 100) (if you change the value, it will turn off white and only do orange)
leda controls orange (values 0 - 255)
ledb controls white (values 0 - 255)
mxc_msp430.0 controls orange (values 0 - 100) (if you change the value, it will turn off white and only do orange)

'led' sets a value between 0% and 100% of the chosen value of 'leda' and 'ledb' (so if you set 'ledb' at 128(~50%), and 'led' at 50(~50%), the screen will output ~25% total brightness (in theory. apparently it can also set it higher, so maybe the scale of 0 - 100, has 0 - 50 = dim 0% - 100%, and 50 - 100 = brighten 0% - 100%?

i tried some things, using:

echo $value > /sys/devices/platform/ntx_bl/backlight/mxc_msp430.0/brightness
echo $value > /sys/class/backlight/lm3630a_led/brightness
echo $value > /sys/class/backlight/lm3630a_leda/brightness
echo $value > /sys/class/backlight/lm3630a_ledb/brightness

'led' can turn down, and off 'leda' and 'ledb'
'led' can turn on 'leda' (not 'ledb')
'mxc_msp430.0' can turn down, on and off 'leda'
'leda' can turn down, on and off 'leda'
'ledb' can turn down, on and off 'ledb'

then i found 'color'

echo (0 - 10) > /sys/class/backlight/lm3630a_led/color
0 = orange, 10 = white. all inbetween, is inbetween.

so for colour tone, use /sys/class/backlight/lm3630a_led/color
for dimming, use 'leda' and 'ledb'

I hope this gives you an idea of how the backlight works?