| commit | c28d427b111b99961dfdb3e0eddb82c36d9f9b61 | |
| author | Henrique de Moraes Holschuh <hmh@hmh.eng.br> | |
| Thu, 9 Oct 2008 18:09:29 +0000 (9 15:09 -0300) | ||
| committer | Henrique de Moraes Holschuh <hmh@hmh.eng.br> | |
| Thu, 9 Oct 2008 18:09:29 +0000 (9 15:09 -0300) | ||
| tree | 68fe2a5fcc7adce58bf26e4e3ae47266547843aa | treesnapshot (tar.gz zip) |
| parent | a541e884f82902ab50ec6ba751efcb996ed878f2 | 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 |