This program is used for communicating with monitor using DDC/CI interface.
This program is GPLed and written by Oleg I. Vdovikin ([email protected])

Use i2cdetect to scan your DDC I2C buses first. Supported displays should
respond at addresses 0x37 (DDC/CI) and 0x50 (EDID). Some displays are respond
on VGA or DVI busses only, so check both.

This program is based on info sniffed on wire and published in 

USB Monitor Control Class 1.0 specification for control codes
available at http://www.usb.org/developers/hidpage/usbmon10.pdf

and

ACCESS.bus (tm) Specifications Version 3.0 available at
http://measure.feld.cvut.cz/groups/micro/soucastky/spec/serial_p/Access_bus_spec_3_0.pdf

In fact, up to date information about DDC/CI standard (Display Data Channel 
Command Interface (DDC/CI) Standard (formerly DDC2Bi), Version 1) is available
from VESA (http://www.vesa.org) and the summary is freely available at
http://www.vesa.org/summary/sumddcci.htm

Tested with Samsung SyncMaster 173T (personally by me) with radeonfb and 
Mitsubishi Diamond Pro 2060u (by Nicolas Boichat) with rivafb. Mitsubishi
Diamond Pro 2060u does not support capabilities request.

Usage:
ddcci-tool [-a adr] [-e] [-d] [-c] [-f] [-v] [-s] [-S] [-r ctrl] [-w value] dev
        dev: device, e.g. /dev/i2c-0
        adr: base address of ddc/ci, eg 0x37 (def)
        -e : query EDID at 0x50
        	queries monitor EDID, which should be accessible at I2C address 0x50
        -c : query capability
        	queries DDC/CI capabilities string
        -d : query ctrls 0 - 255
        	dumps controls 0-255, checking validity byte, use -f to override
        -r : query ctrl
        	specifies control index to read or write (-w)
        -w : value to write to ctrl
        	value for control to be writen for index specified with -r
        -f : force (avoid validity checks)
        	avoid validity check
        -s : save settings
        	Sends DDC/CI command to save adjustments made by -w
        -v : verbosity (specify more to increase)
        	try -v and -vv (low level send/recv) for greater effect
        -S : send Samsung DDC/CI enable
        	seems some of the Samsung monitors requires this for operating

Sample output:
ddcci-tool version 0.03

Reading EDID : 0x50@/dev/i2c-2
	Plug and Play ID: SAM00BA
	Input type: Analog

Using ddc/ci : 0x37@/dev/i2c-2

Capabilities:
(type(LCD)vcp(04 05 06 08 0E 10 12 16 18 1A 1E 20 30 3E 60(1 3) B0(1 2) B6 C6 C8 C9 D6(1 4) DC(1 2 3 4) DF E0(0 1 2)))

Controls (valid/current/max):
Control 0x04: +/0/1	[Reset Factory Defaults]
Control 0x05: +/0/1	[SAM: Reset Brightness and Contrast]
Control 0x06: +/0/1	[Reset Factory Geometry]
Control 0x08: +/0/1	[Reset Factory Default Color]
Control 0x0e: +/60/120	[SAM: Image Lock Coarse]
Control 0x10: +/0/100	[Brightness]
Control 0x12: +/50/100	[Contrast]
Control 0x16: +/8/16	[Red Video Gain]
Control 0x18: +/8/16	[Green Video Gain]
Control 0x1a: +/8/16	[Blue Video Gain]
Control 0x1e: +/0/2	[SAM: Auto Size Center]
Control 0x20: +/50/100	[Horizontal Position]
Control 0x30: +/25/54	[Vertical Position]
Control 0x3e: +/39/50	[SAM: Image Lock Fine]
Control 0x60: +/1/3	[Input Source Select]
Control 0x62: +/0/100	[Audio Speaker Volume Adjust]
Control 0x6c: +/140/255	[Red Video Black Level]
Control 0x6e: +/127/255	[Green Video Black Level]
Control 0x70: +/121/255	[Blue Video Black Level]
Control 0xb0: +/0/2	[Settings]
Control 0xb6: +/3/8	[???]
Control 0xc6: +/1/1	[???]
Control 0xc8: +/5/16	[???]
Control 0xc9: +/1/0	[???]
Control 0xca: +/2/2	[On Screen Display]
Control 0xcc: +/2/11	[SAM: On Screen Display Language]
Control 0xd6: +/1/4	[SAM: DPMS control (1 - on/4 - stby)]
Control 0xdc: +/4/4	[SAM: MagicBright (1 - text/2 - internet/3 - entertain/4 - custom)]
Control 0xdf: +/512/0	[VCP Version]
Control 0xe0: +/0/2	[SAM: Color preset (0 - normal/1 - warm/2 - cool)]
Control 0xe1: +/1/1	[SAM: Power control (0 - off/1 - on)]
Control 0xe2: +/0/1	[???]
Control 0xed: +/108/255	[SAM: Red Video Black Level]
Control 0xee: +/101/255	[SAM: Green Video Black Level]
Control 0xef: +/103/255	[SAM: Blue Video Black Level]