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authorHenrique de Moraes Holschuh <hmh@hmh.eng.br>2009-04-04 00:25:53 -0400
committerLen Brown <len.brown@intel.com>2009-04-04 03:14:53 -0400
commit0e501834f8c2ba7de2a56e332d346dcf4ac0b593 (patch)
tree97aa4223015bbb43ffeced0812b243e42f8ba872 /Documentation/laptops
parent74a60c0f828016456fc635feae388ffd12bb3bb9 (diff)
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')
-rw-r--r--Documentation/laptops/thinkpad-acpi.txt12
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
1157from 0 to 15. 1157from 0 to 15.
1158 1158
1159There are two interfaces to the firmware for direct brightness control, 1159There are two interfaces to the firmware for direct brightness control,
1160EC and CMOS. To select which one should be used, use the 1160EC and UCMS (or CMOS). To select which one should be used, use the
1161brightness_mode module parameter: brightness_mode=1 selects EC mode, 1161brightness_mode module parameter: brightness_mode=1 selects EC mode,
1162brightness_mode=2 selects CMOS mode, brightness_mode=3 selects both EC 1162brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC
1163and CMOS. The driver tries to auto-detect which interface to use. 1163mode with NVRAM backing (so that brightness changes are remembered
1164across shutdown/reboot).
1165
1166The driver tries to select which interface to use from a table of
1167defaults for each ThinkPad model. If it makes a wrong choice, please
1168report this as a bug, so that we can fix it.
1164 1169
1165When display backlight brightness controls are available through the 1170When display backlight brightness controls are available through the
1166standard ACPI interface, it is best to use it instead of this direct 1171standard 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.
1498 (bluetooth, WWAN, UWB...) 1503 (bluetooth, WWAN, UWB...)
1499 0x0008 HKEY event interface, hotkeys 1504 0x0008 HKEY event interface, hotkeys
1500 0x0010 Fan control 1505 0x0010 Fan control
1506 0x0020 Backlight brightness
1501 1507
1502There is also a kernel build option to enable more debugging 1508There is also a kernel build option to enable more debugging
1503information, which may be necessary to debug driver problems. 1509information, which may be necessary to debug driver problems.