BrightnessKeys
Automatic handling of brightness keys based on ACPI Specification, Appendix B: Video Extensions.
Requires Lilu 1.2.0 or newer.
Boot arguments
-brkeysdbgto enable debug printing (available in DEBUG binaries).
Special cases
Typically no DSDT patches are required. Please remove old _Qxx to XQxx ones.
On some models, may be required add ACPI patch _OSI to XOSI and SSDT-XOSI.
Spoiler: On some old ThinkPad models, additional handling may be required.
Here is an example for their "brightness up" EC event.
Method (_Q14, 0, NotSerialized)
{
If (^HKEY.MHKK (0x8000))
{
^HKEY.MHKQ (0x1010) // Vendor-specific event: TP_HKEY_EV_BRGHT_UP
}
If (NBCF) // Whether
{
If (VIGD)
{
Notify (^^^VID.LCD0, 0x86) // Send 0x86 "Increase Brightness" to integrated graphics
}
Else
{
Notify (^^^PEG.VID.LCD0, 0x86) // Send 0x86 "Increase Brightness" to discrete graphics
}
}
Else
{
Local0 = BRLV // Local variable to store current brightness level
If ((Local0 != 0x0F))
{
Local0++
BRLV = Local0
}
If (VIGD)
{
UCMS (0x16) // SMI access for integrated graphics
BRNS ()
}
Else
{
VBRC (Local0) // SMI access for discrete graphics
}
^HKEY.MHKQ (0x6050) // Vendor-specific event: TP_HKEY_EV_BACKLIGHT_CHANGED
}
}
When NBCF is set to zero by default, the method will not notify graphics devices and try to adjust brightness directly. To override that, set NBCF = 0x01 in SSDT hotpatch, or just replace its declaration using a simple patch.
-
For DSDT compiled with older iasl, replace
Name (NBCF, 0x00)toName (NBCF, 0x01):
Find:08 4E424346 0A 00// NameOp "NBCF" BytePrefix "00"
Repl:08 4E424346 0A 01// NameOp "NBCF" BytePrefix "01" -
For DSDT compiled with newer iasl, replace
Name (NBCF, Zero)toName (NBCF, One):
Find:08 4E424346 00// NameOp "NBCF" ZeroOp
Repl:08 4E424346 01// NameOp "NBCF" OneOp