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修复 powertop 始终显示 0 mW 显示器背光使用错误

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本文为早期笔记，可能存在版本过时、命令失效、链接失效、最佳实践变化等问题。请以官方最新文档为准。

原英文标题：Fix the powertop always show 0 mW Display Backlight usage error

今天我安装了 powertop 来监控笔记本电脑上所有设备的功耗。安装后，我立即通过命令 powertop 启动了它。该工具一直显示我的显示器背光功耗为 0 mW，如下所示。

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Power est.    Usage     Device name
  6.48 W     35.1%        CPU core
   0    W    100.0%        Display backlight

我尝试调整了屏幕亮度，"Usage" 列确实会变化，但 "Power est." 列不会变化。

在 Google 搜索后，我安装了 acpi，并尝试通过以下命令关闭显示器：

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xset -d :0 dpms force off

然后轻触触摸板，屏幕重新亮起，正如 GitHub 上 marcelopm 在这个 issue 中所说。

我还编辑了 /etc/default/grub，添加了

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GRUB_CMDLINE_LINUX="acpi_backlight=vendor"

并通过以下命令重新生成了 grub.cfg：

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sudo grub-mkconfig /boot/grub/grub.cfg

最终的解决方案是上述操作，再加上使用以下命令校准 powertop：

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sudo powertop --calibrate

然后它就恢复正常了。

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The battery reports a discharge rate of 15.2 W
The energy consumed was 409 J
System baseline power is estimated at 24.3 W

Power est.    Usage     Device name
  13.8 W    100.0%        Display backlight
  6.73 W    236.9%        CPU core
  3.71 W    236.9%        CPU misc
 44.0 mW      9.6 pkts/s  Network interface: wlp1s0 (iwlwifi)
    0 mW    100.0%        Radio device: iwlwifi
    0 mW      0.0%        USB device: HP HD Camera (Chicony)
    0 mW      0.0%        USB device: usb-device-8087-0a2b
    0 mW      0.0%        USB device: xHCI Host Controller
    0 mW      0.0%        USB device: usb-device-138a-003f
    0 mW      0.0%        USB device: xHCI Host Controller
    0 mW      0.0%        Audio codec hwC0D0: Conexant
    0 mW      0.0%        Radio device: btusb
            100.0%        PCI Device: Intel Corporation Sunrise Point-LP LPC Controller

1. 原文（English）

Today I installed powertop to monitor the power consumption of all the devices on my laptop. After installing, I immediately launched it by command powertop. And the utility always show me that my display backlight consumes 0 mW of power, like this.

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Power est.    Usage     Device name
  6.48 W     35.1%        CPU core
   0    W    100.0%        Display backlight

I tried to adjust the screen brightness, the "Usage" column did change, but the "Power est." column wouldn't.

After Googling, I installed acpi , and tried tuning off the display by

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xset -d :0 dpms force off

then tapped touchpad and screen went on, just as marcelopm said in this issue on GitHub.

I also edited /etc/default/grub, added

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GRUB_CMDLINE_LINUX="acpi_backlight=vendor"

and regenerated grub.cfg by

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sudo grub-mkconfig /boot/grub/grub.cfg

The final solution was it and to calibrate powertop with

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sudo powertop --calibrate

Then it became normal.

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The battery reports a discharge rate of 15.2 W
The energy consumed was 409 J
System baseline power is estimated at 24.3 W

Power est.    Usage     Device name
  13.8 W    100.0%        Display backlight
  6.73 W    236.9%        CPU core
  3.71 W    236.9%        CPU misc
 44.0 mW      9.6 pkts/s  Network interface: wlp1s0 (iwlwifi)
    0 mW    100.0%        Radio device: iwlwifi
    0 mW      0.0%        USB device: HP HD Camera (Chicony)
    0 mW      0.0%        USB device: usb-device-8087-0a2b
    0 mW      0.0%        USB device: xHCI Host Controller
    0 mW      0.0%        USB device: usb-device-138a-003f
    0 mW      0.0%        USB device: xHCI Host Controller
    0 mW      0.0%        Audio codec hwC0D0: Conexant
    0 mW      0.0%        Radio device: btusb
            100.0%        PCI Device: Intel Corporation Sunrise Point-LP LPC Controller