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gnome屏幕亮度

tag-icon • tag-icon gnome kernel brightness mac
gnome屏幕亮度

当按下亮度键（或使用设置中的滑块）时，Ubuntu 会表现得好像在改变屏幕亮度，但亮度并没有改变。通过四处寻找，我发现我可以使用

echo $N > /sys/class/backlight/radeon_bl0/brightness

其中 $N >= 0 且 $N <= 255。

  • iMac=mc813ll/a
  • Ubuntu 版本=18.04
  • 内核=4.15.0-20-generic（默认）

相关日志摘录；

> tail -n 2 /var/log/auth.log
May  5 11:44:02 imac pkexec: pam_unix(polkit-1:session): session opened for user root by (uid=1000)
May  5 11:44:02 imac pkexec[7310]: $USER: Executing command [USER=root] [TTY=unknown] [CWD=/home/$USER] [COMMAND=/usr/lib/gnome-settings-daemon/gsd-backlight-helper --set-brightness 10]

直接测试；

> sudo /usr/lib/gnome-settings-daemon/gsd-backlight-helper --set-brightness 255
Could not set the value of the backlight: writing '255' to /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/backlight/acpi_video0 failed

没有手册页

> man gsd-backlight-helper
No manual entry for gsd-backlight-helper
> man gnome-settings-daemon
No manual entry for gnome-settings-daemon

更长的路径示例；

> echo 20 > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/backlight/acpi_video0/brightness
-bash: echo: write error: Invalid argument

> echo 20 > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-eDP-1/radeon_bl0/brightness

好像这是 src，我如何告诉 GNOME 亮度与内核中的什么对话？

[编辑] 我刚刚重启，

/sys/class/backlight/radeon_bl0/brightness

就是现在

/sys/class/backlight/radeon_bl1/brightness

或者

/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card1/card1-eDP-1/radeon_bl1

所以位置并不稳定。

> lspci | grep "VGA compatible controller"
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Whistler [Radeon HD 6730M/6770M/7690M XT]

> sudo dmidecode | grep -A 9 "System Information" | grep "Product Name"
    Product Name: iMac12,2

答案1

使用acpi_backlight核参数；

 sudo perl -pi -e 's/(GRUB_CMDLINE_LINUX_DEFAULT="[^"]*)(")/$1 acpi_backlight=vendor$2/g' /etc/default/grub

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