/Documentation/power/video_extension.txt

 1ACPI video extensions
 2~~~~~~~~~~~~~~~~~~~~~
 3
 4This driver implement the ACPI Extensions For Display Adapters for
 5integrated graphics devices on motherboard, as specified in ACPI 2.0
 6Specification, Appendix B, allowing to perform some basic control like
 7defining the video POST device, retrieving EDID information or to
 8setup a video output, etc.  Note that this is an ref. implementation
 9only.  It may or may not work for your integrated video device.
10
11Interfaces exposed to userland through /proc/acpi/video:
12
13VGA/info : display the supported video bus device capability like Video ROM, CRT/LCD/TV.
14VGA/ROM :  Used to get a copy of the display devices' ROM data (up to 4k).
15VGA/POST_info : Used to determine what options are implemented.
16VGA/POST : Used to get/set POST device.
17VGA/DOS : Used to get/set ownership of output switching:
18	Please refer ACPI spec B.4.1 _DOS
19VGA/CRT : CRT output
20VGA/LCD : LCD output
21VGA/TVO : TV output
22VGA/*/brightness : Used to get/set brightness of output device
23
24Notify event through /proc/acpi/event:
25
26#define ACPI_VIDEO_NOTIFY_SWITCH        0x80
27#define ACPI_VIDEO_NOTIFY_PROBE         0x81
28#define ACPI_VIDEO_NOTIFY_CYCLE         0x82
29#define ACPI_VIDEO_NOTIFY_NEXT_OUTPUT   0x83
30#define ACPI_VIDEO_NOTIFY_PREV_OUTPUT   0x84
31
32#define ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS      0x82
33#define ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS        0x83
34#define ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS        0x84
35#define ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS       0x85
36#define ACPI_VIDEO_NOTIFY_DISPLAY_OFF           0x86
37