| commit | 37ce6a27c903439a8f3d0c7737bfc104ee01f12c | |
| author | Henrique de Moraes Holschuh <hmh@hmh.eng.br> | |
| Mon, 17 Mar 2008 00:12:43 +0000 (16 21:12 -0300) | ||
| committer | Henrique de Moraes Holschuh <hmh@hmh.eng.br> | |
| Fri, 21 Mar 2008 23:43:57 +0000 (21 20:43 -0300) | ||
| tree | cf65884c0a1a4fd8db12db42263ad718bf4078d0 | treesnapshot (tar.gz zip) |
| parent | e80b84fd7e2156d202b7bf78ccb80095a50b5d25 | 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 |