| commit | 7ee1731d904e51ba38870dbe8b30fdfb1f672161 | |
| author | Henrique de Moraes Holschuh <hmh@hmh.eng.br> | |
| Tue, 11 Nov 2008 01:46:04 +0000 (10 23:46 -0200) | ||
| committer | Henrique de Moraes Holschuh <hmh@hmh.eng.br> | |
| Tue, 11 Nov 2008 01:46:04 +0000 (10 23:46 -0200) | ||
| tree | ecb8029fc3b6b434c2f9bd5d15364fdc031f61d0 | treesnapshot (tar.gz zip) |
| parent | ce3b97e4f6aee2b875c189b98079a4eda335722e | commitdiff |
ACPI: thinkpad-acpi: fix brightness dimming control bug
ibm-acpi and thinkpad-acpi did not know about bit 5 of the EC backlight
level control register (EC 0x31), so it was always forced to zero on
any writes.
This would disable the BIOS option to *not* use a dimmer backlight level
scale while on battery, and who knows what else (there are two other
control bits of unknown function).
Bit 5 controls the "reduce backlight levels when on battery" optional
functionality (active low). Bits 6 and 7 are better left alone as well,
instead of being forced to zero.
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
ibm-acpi and thinkpad-acpi did not know about bit 5 of the EC backlight
level control register (EC 0x31), so it was always forced to zero on
any writes.
This would disable the BIOS option to *not* use a dimmer backlight level
scale while on battery, and who knows what else (there are two other
control bits of unknown function).
Bit 5 controls the "reduce backlight levels when on battery" optional
functionality (active low). Bits 6 and 7 are better left alone as well,
instead of being forced to zero.
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
| drivers/misc/thinkpad_acpi.c | diffblobblamehistory |