Debian 9：背光亮度

Question

我刚刚将带有 LXDE 的全新 Debian 9 安装到 ACER AMD 笔记本电脑中，除了背光亮度外，一切似乎都运行良好。在启动过程中，会发生以下情况：

• 出现 多条消息和错误

  [FAILED] Failed to start Load/Save Screen Backlight Brightness of backlight:acpi_video0.
  See 'systemctl status systemd-backlight@backlight:acpi_video0.service' for details.
  Starting Load/Save Screen Backlight Brightness of backlight:radeon_bl0
  ...
  [ OK ] Started Load/Save Screen Backlight Brightness of backlight:radeon_bl0
  

• 通常背光亮度被重置为最大

为了将背光亮度设置为可接受的水平，目前最好的解决方案似乎是打开终端并在 Debian 初始化后立即键入以下命令行：

• tee /sys/class/backlight/radeon_bl0/brightness <<< 15

 

问题

1. 如何避免开机时背光亮度被重置为最大？
2. 如何设置背光亮度的快捷方式（例如：）[Fn] + ?/?？

 

---

调试

root@debian:~# dmesg | grep -i "error\|firmware\|backlight"
[    1.049855] pci 0000:01:00.0: [Firmware Bug]: disabling VPD access (can't determine size of non-standard VPD format)
[    7.729996] EXT4-fs (sda1): re-mounted. Opts: errors=remount-ro
[   12.960474] radeon 0000:00:01.0: firmware: direct-loading firmware radeon/PALM_pfp.bin
[   13.017938] radeon 0000:00:01.0: firmware: direct-loading firmware radeon/PALM_me.bin
[   13.043827] radeon 0000:00:01.0: firmware: direct-loading firmware radeon/SUMO_rlc.bin
[   13.161157] radeon 0000:00:01.0: firmware: direct-loading firmware radeon/SUMO_uvd.bin
[   13.897112] [drm] radeon atom DIG backlight initialized

 

root@debian:~# systemctl status systemd-backlight@backlight:acpi_video0.service
? systemd-backlight@backlight:acpi_video0.service - Load/Save Screen Backlight Brightness of backlight:acpi_video0
   Loaded: loaded (/lib/systemd/system/systemd-backlight@.service; static; vendor preset: enabled)
   Active: failed (Result: exit-code) since Sat 2018-06-16 06:37:19 -03; 29min ago
     Docs: man:systemd-backlight@.service(8)
  Process: 411 ExecStart=/lib/systemd/systemd-backlight load backlight:acpi_video0 (code=exited, status=1/FAILURE)
 Main PID: 411 (code=exited, status=1/FAILURE)

Jun 16 06:37:19 debian systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:acpi_video0...
Jun 16 06:37:19 debian systemd[1]: systemd-backlight@backlight:acpi_video0.service: Main process exited, code=exited, status=1/FAILURE
Jun 16 06:37:19 debian systemd[1]: Failed to start Load/Save Screen Backlight Brightness of backlight:acpi_video0.
Jun 16 06:37:19 debian systemd[1]: systemd-backlight@backlight:acpi_video0.service: Unit entered failed state.
Jun 16 06:37:19 debian systemd[1]: systemd-backlight@backlight:acpi_video0.service: Failed with result 'exit-code'.

---

硬件规格
笔记本Aspire E1-421-0622 | 产品详情

• AMD 2 核™ 处理器 E1-1200 (1.4 GHz) 1MB 缓存 64 位处理
• AMD Radeon HD 7310 图形控制器
• 2Gb DDR3 SDRAM 内存
• 256MB 共享显存

 

Debian
Strech debian-9.4.0-amd64-netinst.iso

• 小CD
• AMD64处理器架构
• R600 或更高版本的非免费软件包firmware-amd-graphics安装
  radeon 内核模式设置需要固件-amd-graphics
• 软件选择
  ( ) Debian 桌面环境
  ( ) ... GNOME
  ( ) ... Xfce
  ( ) ... KDE
  ( ) ... Cinnamon
  ( ) ... MATE
  (X) ... LXDE
  ( ) Web 服务器
  (X ) 打印服务器
  ( ) SSH 服务器
  (X) 标准系统实用程序

Answer 1

您的系统似乎有两个用于背光控制的接口：backlight:acpi_video0和backlight:radeon_bl0。显然，ACPI 接口不起作用，并且/或与 Radeon 特定接口一起使用时会导致问题。

由于 Radeon 特定的接口似乎工作正常，我会尝试告诉 systemd 首先停止使用 ACPI 背光接口：

systemctl mask systemd-backlight@backlight:acpi_video0.service

如有必要，可以通过以下方式撤消此操作：

systemctl unmask systemd-backlight@backlight:acpi_video0.service

如果这没有帮助，则需要进一步调查。

这样journalctl -xb您应该能够看到仅针对当前启动的相当详细的消息版本。默认情况下，Debian 9 中未启用 systemd 日志的持久存储，但启用它非常容易：只需mkdir /var/log/journal以 root 身份运行即可。然后，从下次启动开始，日志将被持久存储，您将能够使用例如查看上次启动从启动到关闭的日志journalctl -xb -1。最旧的日志最终将被自动清除，由journald可用磁盘空间的可配置标准控制。