https://justpaste.it/5jszu

 

I tried with I2C connected and disconnected between screen and tinkerboard.  No change. (See below, looks like i2c-3/3-0045/tinker_mcu_bl is missing ).   I checked around that area and tinker_mcu_bl is missing, but folder 3-0045 exists with lots of files in there. (bottom of the post)

 

From dmesg I also see that i2c had a failure (ret = -6). (see next paste)

 

Looking forward I see that -6 is no device found on i2c bus (assuming that's correct?). Does anyone know if brightness control works?

 

 

[    2.446829] tinker-mcu: tinker_mcu_probe: address = 0x45   
[    2.446843] tinker-mcu: send_cmds: 80  
[    2.493126] tinker-mcu: init_cmd_check: recv_cmds: 0xC3    
[    3.161121] tinker_mcu_screen_power_up 
[    3.161122] tinker-mcu: tinker_mcu_screen_power_up:   
[    3.161127] tinker-mcu: send_cmds: 8500     
[    4.545081] tinker-mcu: send_cmds: 8501     
[    4.569108] tinker-mcu: send_cmds: 8104     
[    4.572138] tinker-mcu: send_cmds: send command failed, ret = -6     
[    4.574293] tinker-mcu: tinker_mcu_set_bright: bright = 0xff 

 

shadowpho@tinkerboard:~$ sudo rpi-backlight -Btinker-board -p toggle    
Traceback (most recent call last):    
File "/usr/local/bin/rpi-backlight", line 10, in <module>  sys.exit(main())     
File "/usr/local/lib/python3.7/dist-packages/rpi_backlight/cli.py", line 103, in main   if backlight.power:  
File "/usr/local/lib/python3.7/dist-packages/rpi_backlight/__init__.py", line 213, in power     return bool(self._get_value("tinker_mcu_bl"))     
File "/usr/local/lib/python3.7/dist-packages/rpi_backlight/__init__.py", line 85, in _get_value raise e     
File "/usr/local/lib/python3.7/dist-packages/rpi_backlight/__init__.py", line 77, in _get_value return int((self._backlight_sysfs_path / name).read_text())    
File "/usr/lib/python3.7/pathlib.py", line 1199, in read_text with self.open(mode='r', encoding=encoding, errors=errors) as f: 
File "/usr/lib/python3.7/pathlib.py", line 1186, in open   opener=self._opener) 
File "/usr/lib/python3.7/pathlib.py", line 1039, in _opener   return self._accessor.open(self, flags, mode)   FileNotFoundError: [Errno 2] No such file or directory: '/sys/devices/platform/ff150000.i2c/i2c-3/3-0045/tinker_mcu_bl'   

 

Oh no. Then I updated to 21.02.03 with 5.10.21-rockchip and now the display doesn't work at all

Sorry for post in old topic, but I can't change brightness via GUI on my ASUS tinker board (RK3288) with Ubuntu focal (21.05.8 + kernel 5.10.43-rockchip) and LXQt.
I tried to change brightness from terminal with: xbacklight, xrandr and rpi-backlight - it did not help, but ddcutil (DDC/CI - Display Data Channel Command Interface):

// make sure, that feature 10 is brightness
$ sudo ddcutil capabilities | grep "Feature: 10"
  Feature: 10 (Brightness)
// get current brightness
$ ddcutil getvcp 10
VCP code 0x10 (Brightness                    ): current value =    60, max value =   100
// set current brightness
$ sudo ddcutil setvcp 10 40

 

Some more info about ddcutil can be found on Arch wiki: https://wiki.archlinux.org/title/backlight#External_monitors
 

I'm fine with changing brightness from terminal for now, but if you know better solution - post it here, please.