diff options
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 | |||
1157 | from 0 to 15. | 1157 | from 0 to 15. |
1158 | 1158 | ||
1159 | There are two interfaces to the firmware for direct brightness control, | 1159 | There are two interfaces to the firmware for direct brightness control, |
1160 | EC and CMOS. To select which one should be used, use the | 1160 | EC and UCMS (or CMOS). To select which one should be used, use the |
1161 | brightness_mode module parameter: brightness_mode=1 selects EC mode, | 1161 | brightness_mode module parameter: brightness_mode=1 selects EC mode, |
1162 | brightness_mode=2 selects CMOS mode, brightness_mode=3 selects both EC | 1162 | brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC |
1163 | and CMOS. The driver tries to auto-detect which interface to use. | 1163 | mode with NVRAM backing (so that brightness changes are remembered |
1164 | across shutdown/reboot). | ||
1165 | |||
1166 | The driver tries to select which interface to use from a table of | ||
1167 | defaults for each ThinkPad model. If it makes a wrong choice, please | ||
1168 | report this as a bug, so that we can fix it. | ||
1164 | 1169 | ||
1165 | When display backlight brightness controls are available through the | 1170 | When display backlight brightness controls are available through the |
1166 | standard ACPI interface, it is best to use it instead of this direct | 1171 | 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. | |||
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 | ||
1502 | There is also a kernel build option to enable more debugging | 1508 | There is also a kernel build option to enable more debugging |
1503 | information, which may be necessary to debug driver problems. | 1509 | information, which may be necessary to debug driver problems. |