Ev3dev: brightness level doesn't work (ev3dev-stretch, Lego EV3, LEDS)

[xdsl]

I try to change the brightness level:

1. echo 255 > /sys/class/leds/led0:green:brick-status/brightness
2. echo 100 > /sys/class/leds/led0:green:brick-status/brightness
3. echo 10 > /sys/class/leds/led0:green:brick-status/brightness

The result of all options is identical: the brightness level remains the maximum.

System:

Image file: ev3dev-stretch-ev3-generic-2018-08-06
Kernel version: 4.14.61-ev3dev-2.2.2-ev3
Brickman: 0.10.0
BogoMIPS: 148.88
Board: board0
BOARD_INFO_HW_REV=7
BOARD_INFO_MODEL=LEGO MINDSTORMS EV3
BOARD_INFO_ROM_REV=6
BOARD_INFO_SERIAL_NUM=0016534C8680
BOARD_INFO_TYPE=main

[jabrena]

Good morning,

What is the Debian Stretch image that you used?

[xdsl]

https://github.com/ev3dev/ev3dev/releases/download/ev3dev-stretch-2018-08-06/ev3dev-stretch-ev3-generic-2018-08-06.zip

[jabrena]

I reviewed your paths and they are ok:
https://github.com/ev3dev-lang-java/ev3dev-lang-java/blob/feature/%23443/src/main/resources/stretch.properties#L45

I will test it today.

Juan Antonio

[xdsl]

paths is ok, but brightness level doesn't change
if you send zero, the led will turn off
if you send nonzero, the led will light up on maximum brightness

[dlech]

The brightness feature was removed in ev3dev-stretch.

[WasabiFan]

Woah, really? Was that to avoid the overhead of bit-banging PWM?

[xdsl]

Very bad. This is a regression.

[dlech]

The pwm-gpio driver is not not in the mainline kernel, and I didn't port it to the newer kernel. However, now that we have use of one of the PRUs we could actually make a better PWM using that.

[dlech]

Fix has been released in 2.3.0-ev3dev kernel.