亮度 backlight brightness

 $ xgamma -gamma .7 

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             GRUB_CMDLINE_LINUX="acpi_osi= acpi_backlight=intel" 

1. Intel - nomodeset acpi_backlight=intel
2. Acer - acpi_backlight=acer_acpi
3. acpi_osi=Linux acpi_backlight=legacy.

pcie_aspm=force i915.semaphores=1 acpi_osi=Linux acpi_backlight=vendor elevator=noop i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1