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| author | Henrique de Moraes Holschuh <hmh@hmh.eng.br> | 2009-04-04 04:25:53 +0000 |
|---|---|---|
| committer | Len Brown <len.brown@intel.com> | 2009-04-04 03:14:53 -0400 |
| commit | 0e501834f8c2ba7de2a56e332d346dcf4ac0b593 (patch) | |
| tree | 97aa4223015bbb43ffeced0812b243e42f8ba872 /Documentation/laptops/thinkpad-acpi.txt | |
| parent | 74a60c0f828016456fc635feae388ffd12bb3bb9 (diff) | |
| download | lwn-0e501834f8c2ba7de2a56e332d346dcf4ac0b593.tar.gz lwn-0e501834f8c2ba7de2a56e332d346dcf4ac0b593.zip | |
thinkpad-acpi: rework brightness support
Refactor and redesign the brightness control backend...
In order to fix bugzilla #11750...
Add a new brightness control mode: support direct NVRAM checkpointing
of the backlight level (i.e. store directly to NVRAM without the need
for UCMS calls), and use that together with the EC-based control.
Disallow UCMS+EC, thus avoiding races with the SMM firmware.
Switch the models that define HBRV (EC Brightness Value) in the DSDT
to the new mode. These are: T40-T43, R50-R52, R50e, R51e, X31-X41.
Change the default for all other IBM ThinkPads to UCMS-only. The
Lenovo models already default to UCMS-only.
Reported-by: Alexey Fisher <bug-track@fisher-privat.net>
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'Documentation/laptops/thinkpad-acpi.txt')
| -rw-r--r-- | Documentation/laptops/thinkpad-acpi.txt | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/Documentation/laptops/thinkpad-acpi.txt b/Documentation/laptops/thinkpad-acpi.txt index 25ed43d0a21f..3d7650768bb5 100644 --- a/Documentation/laptops/thinkpad-acpi.txt +++ b/Documentation/laptops/thinkpad-acpi.txt @@ -1157,10 +1157,15 @@ display backlight brightness control methods have 16 levels, ranging from 0 to 15. There are two interfaces to the firmware for direct brightness control, -EC and CMOS. To select which one should be used, use the +EC and UCMS (or CMOS). To select which one should be used, use the brightness_mode module parameter: brightness_mode=1 selects EC mode, -brightness_mode=2 selects CMOS mode, brightness_mode=3 selects both EC -and CMOS. The driver tries to auto-detect which interface to use. +brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC +mode with NVRAM backing (so that brightness changes are remembered +across shutdown/reboot). + +The driver tries to select which interface to use from a table of +defaults for each ThinkPad model. If it makes a wrong choice, please +report this as a bug, so that we can fix it. When display backlight brightness controls are available through the standard ACPI interface, it is best to use it instead of this direct @@ -1498,6 +1503,7 @@ to enable more than one output class, just add their values. (bluetooth, WWAN, UWB...) 0x0008 HKEY event interface, hotkeys 0x0010 Fan control + 0x0020 Backlight brightness There is also a kernel build option to enable more debugging information, which may be necessary to debug driver problems. |