LED use, customization ?

[lat]

Oh, thank you @dukla2000!  I've tried exactly that, but didn't realize that those LED flashes were very brief, so I simply did not see them!

Now it would be nice to figure out how to use the full range of LED signals (solid, flashing with different frequencies, two/three LEDs simultaneously) for any user-specified device state (missed call, new sms/email, no_network_connection, etc, etc).  I recall that Maemo on the good old nokia N900 had those highly customizable options in user Settings.  It's successor Maemo Leste (which is easily accessible from Megi's multi-distro image) lists these options in 
Settings -> Notification Light

1. Device on
   
2. Missed call
   
3. Text message received
   
4. E-mail message received
   
5. Instant message received
   

I've briefly looked into Maemo Leste's relevant directories/files, finding these:

Code:

root@devuan-pinephone:/# find / -name leds
/home/user/.gconf/system/osso/dsm/leds
/sys/class/leds
/sys/devices/platform/leds
/sys/devices/platform/leds/leds
/sys/devices/platform/led-controller/leds
/sys/bus/platform/devices/leds
/sys/bus/platform/drivers/leds-gpio/leds
/sys/firmware/devicetree/base/leds

root@devuan-pinephone:/# find / -name '*indicator*'
/sys/class/leds/blue:indicator
/sys/class/leds/red:indicator
/sys/class/leds/green:indicator
/sys/devices/platform/leds/leds/blue:indicator
/sys/devices/platform/leds/leds/red:indicator
/sys/devices/platform/leds/leds/green:indicator

root@devuan-pinephone:~# find / -name led
/sys/devices/platform/soc/1c2ac00.i2c/i2c-1/1-005d/input/input4/capabilities/led
/sys/devices/platform/soc/1c21800.lradc/input/input2/capabilities/led
/sys/devices/platform/soc/1f03400.rsb/sunxi-rsb-3a3/axp221-pek/input/input1/capabilities/led
/sys/devices/platform/vibrator/input/input3/capabilities/led
/sys/devices/platform/sound/sound/card2/input5/capabilities/led
/sys/firmware/devicetree/base/led-controller/led

# cat /sys/devices/platform/soc/1c2ac00.i2c/i2c-1/1-005d/input/input4/capabilities/led
0
# cat /sys/devices/platform/soc/1c21800.lradc/input/input2/capabilities/led
0
# cat /sys/devices/platform/vibrator/input/input3/capabilities/led
0
# cat /sys/devices/platform/sound/sound/card2/input5/capabilities/led
0
# cat /sys/firmware/devicetree/base/led-controller/led

# cd /sys/firmware/devicetree/base/led-controller/led
root@devuan-pinephone:/sys/firmware/devicetree/base/led-controller/led# ls -al
total 0
drwxr-xr-x 2 root root 0 May 29 00:09 .
drwxr-xr-x 3 root root 0 May 29 00:09 ..
-r--r--r-- 1 root root 4 May 29 00:13 color
-r--r--r-- 1 root root 4 May 29 00:13 flash-max-timeout-us
-r--r--r-- 1 root root 6 May 29 00:13 function
-r--r--r-- 1 root root 4 May 29 00:13 name

root@devuan-pinephone:/sys/firmware/devicetree/base/led-controller/led# cat color
root@devuan-pinephone:/sys/firmware/devicetree/base/led-controller/led# cat flash-max-timeout-us
А
root@devuan-pinephone:/sys/firmware/devicetree/base/led-controller/led# cat function
flash
root@devuan-pinephone:/sys/firmware/devicetree/base/led-controller/led# cat name
led

I don't know how these connect with the user applications like email, sms, etc.  Maybe someone more knowlegeable can pick up and take this further...  Come on, Prometeus, bring us some LED light!