NOTES.md

EDID

• https://en.wikipedia.org/wiki/Extended_Display_Identification_Data

• EDID structure versions range from v1.0 to v1.4 (plus a v2.0 - released and deprecated)

• HDMI 1.0 – 1.3c uses EDID structure v1.3

• Enhanced EDID was introduced at the same time as E-DDC

• DDC is the protocol for reading EDID data.

  • E-DDC (Enhanced Display Data Channel) is the most recent revision of the DDC standard.

  • DDC/CI is a control protocol for contrast / etc

    • Most DDC/CI monitors support only a small subset of MCCS commands and some have undocumented commands. Many manufacturers did not pay attention to DDC/CI in the past, but now almost all monitors support such general MCCS commands as brightness and contrast management.

    • Tool / Library - GPLv2

      • http://ddccontrol.sourceforge.net/
      • http://www.boichat.ch/nicolas/ddcci/specs.html

• DisplayID is a VESA standard designed to replace E-EDID standard and EDID structure v1.4

Release Date	Standard Name	EDID structures
August 1994	DDC standard version 1	EDID v1.0 structure
April 1996	EDID standard version 2	EDID v1.1 structure
?????? 1997	EDID standard version 3	EDID structures v1.2 and v2.0
February 2000	E-EDID Standard Release A, v1.0	EDID structure v1.3, EDID structure v2.0 deprecated
September 2006	E-EDID Standard Release A, v2.0	EDID structure v1.4

• EIA/CEA-861 extension block

Version	Spec	Release Date	Notes
Version 1	-861
Version 2	-861A
Version 3	-861B		HDMI 1.0 -1.3c uses this version
	-861D	July 2006
	-861E
	-861F	June 4, 2013

Libraries

• Will use Linux version.
• Fall back is coreboot.

Questions

• How active is the development of the file? When was it last updated?
• License?
• Does it support HDMI EDID extensions?
• Does it use malloc / etc?
• Is it a library?
• Can it generate EDID too?

Linux Kernel

• drivers/gpu/drm/drm_edid.c
• http://lxr.free-electrons.com/source/drivers/gpu/drm/drm_edid.c
• Lots of active development.
• Has lots of quirks support.

coreboot - lib/edid.c

• http://review.coreboot.org/gitweb?p=coreboot.git;a=blob;f=src/lib/edid.c
• Lots, last late 2015
• GPLv3

openxt/libedid

• https://github.com/OpenXT/libedid
• 2 commits, last 2014
• LGPLv2.1

libminitru

• http://cgit.freedesktop.org/~ajax/libminitru/tree/edid.c

u-boot

• https://github.com/ynezz/u-boot-edid/blob/master/edid.c

xorg edid-decode

• http://cgit.freedesktop.org/xorg/app/edid-decode/tree/
• MIT? X11 Maybe?

read-edid

• http://www.polypux.org/projects/read-edid/