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Lenovo ThinkPads with generic ACPI backlight level control can be easily set to react to keyboard brightness key presses in a more predictable way than what they do when in "DOS / bootloader" mode after Linux brings up the ACPI interface. The switch to the ACPI backlight mode in the firmware is designed to be safe to use only as an one way trapdoor. One is not to force the firmware to switch back to "DOS/bootloader" mode except by rebooting. The mode switch itself is performed by calling any of the ACPI _BCL methods at least once. When in ACPI mode, the backlight firmware just issues (standard) events for the brightness up/down hot key presses along with the non-standard HKEY events which thinkpad-acpi traps, and doesn't touch the hardware. thinkpad-acpi will: 1. Place the ThinkPad firmware in ACPI backlight control mode if one is available 2. Suppress HKEY backlight change notifications by default to avoid double-reporting when ACPI video is loaded when the ThinkPad is in ACPI backlight control mode 3. Urge the user to load the ACPI video driver The user is free to use either the ACPI video driver to get the brightness key events, or to override the thinkpad-acpi default hotkey mask to get them from thinkpad-acpi as well (this will result in duplicate events if ACPI video is loaded, so let's hope distros won't screw this up). Provided userspace is sane, all should work (and *keep* working), which is more that can be said about the non-ACPI mode of the new Lenovo ThinkPad BIOSes when coupled to current userspace and X.org drivers. Full guidelines for backlight hot key reporting and use of the thinkpad-acpi backlight interface have been added to the documentation. Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br> Cc: Matthew Garrett <mjg59@srcf.ucam.org> Cc: Thomas Renninger <trenn@suse.de> Signed-off-by: Len Brown <len.brown@intel.com> |
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| .. | ||
| 00-INDEX | ||
| acer-wmi.txt | ||
| laptop-mode.txt | ||
| sony-laptop.txt | ||
| sonypi.txt | ||
| thinkpad-acpi.txt | ||