How to set bytes of EDID on a i2c device

Question

I have a monitor LG E2251 (monitor details).

My computer was connected to the monitor via DVI-I cable; after the power supply broke, the display went black. I rebooted the system and all seemed ok. I pass the POST as usual, however I cannot see the GUI nor CLI when connected with DVI-I. I believe the EDID code for DVI-I has been corrupted. I also tried with other 2 connections: whether HDMI doesn't present any damge,I get the following message for DVI-I

nouveau 0000:01:00.0: DRM: VRAM: 1024 MiB
[    9.292129] nouveau 0000:01:00.0: DRM: GART: 1048576 MiB
[    9.292133] nouveau 0000:01:00.0: DRM: TMDS table version 2.0
[    9.292135] nouveau 0000:01:00.0: DRM: DCB version 4.0
[    9.292137] nouveau 0000:01:00.0: DRM: DCB outp 00: 01000302 00020030
[    9.292139] nouveau 0000:01:00.0: DRM: DCB outp 01: 02000300 00000000
[    9.292141] nouveau 0000:01:00.0: DRM: DCB outp 02: 02011362 00020010
[    9.292143] nouveau 0000:01:00.0: DRM: DCB outp 03: 01022310 00000000
[    9.292145] nouveau 0000:01:00.0: DRM: DCB conn 00: 00001030
[    9.292146] nouveau 0000:01:00.0: DRM: DCB conn 01: 00002161
[    9.292148] nouveau 0000:01:00.0: DRM: DCB conn 02: 00000200
[    9.296293] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[    9.296294] [drm] Driver supports precise vblank timestamp query.
[    9.309393] nouveau 0000:01:00.0: DRM: MM: using COPY for buffer copies
 [drm:drm_edid_block_valid [drm]] *ERROR* EDID checksum is invalid, remainder is 185
[    9.449801] nouveau 0000:01:00.0: DVI-I-1: EDID block 0 invalid.
[    9.449803] nouveau 0000:01:00.0: DRM: DDC responded, but no EDID for DVI-I-1
[    9.470675] nouveau 0000:01:00.0: No connectors reported connected with modes
[    9.470678] [drm] Cannot find any crtc or sizes - going 1024x768
[    9.472105] nouveau 0000:01:00.0: DRM: allocated 1024x768 fb: 0x70000, bo ffff9d41b8eafc00
[    9.472196] fbcon: nouveaufb (fb0) is primary device
[    9.474979] Console: switching to colour frame buffer device 128x48
[    9.476170] nouveau 0000:01:00.0: fb0: nouveaufb frame buffer device
[    9.508021] [drm] Initialized nouveau 1.3.1 20120801 for 0000:01:00.0 on minor 0

and a similar one for VGA

 [drm:drm_edid_block_valid [drm]] *ERROR* EDID checksum is invalid, remainder is 198
[   95.783329] nouveau 0000:01:00.0: VGA-1: EDID block 0 invalid.
[   95.783331] nouveau 0000:01:00.0: DRM: DDC responded, but no EDID for VGA-1

MY APPROACH

• installed i2c-tools on my debian machine.
• found i2c-1 to be my DVI interface
• with i2cdump -y 1 0x50 I can dump the EDID code.

i2cset

However, when I want to set a block of bytes with
i2cset -y 1 0x50 0x00 0x00 0xff i EDID does not change.

How can I correct those EDID? Is there a fast solution in the UserSpace, without assembly programming?

I say I'm new to EDID, nouveau driver, I2C or SMBus communication. Any advice and correction is appreciated.

It looks like I could send BLOCKs of bytes on that I2C BUS i2cdetect -F 1:

Functionalities implemented by /dev/i2c-1:
I2C Block Write                  yes
I2C Block Read                   yes
...

but I don't know what's wrong.

LINKS

• wikipedia/EDID
• read EDID
• i2cget
• i2cset

Answer 1

I don't know if this helps, but I found the EDID dumps matching your monitor model (to compare with your dump).

LG Electronics Inc. (GoldStar Technology, Inc.) E2251

https://github.com/linuxhw/EDID

MFG       Model    Name   Res        Size       Inch  Made  ID
Goldstar  GSM586D  E2251  1920x1080  480x270mm  21.7  2011  8A799
Goldstar  GSM586E  E2251  1920x1080  480x270mm  21.7  2011  011A9
Goldstar  GSM586E  E2251  1920x1080  480x270mm  21.7  2011  2F15B
Goldstar  GSM586E  E2251  1920x1080  480x270mm  21.7  2011  F721B
Goldstar  GSM586F  E2251  1920x1080  480x270mm  21.7  2011  2CA66

• 8A799
• 011A9
• 2F15B
• F721B
• 2CA66

If you have Windows you should try Powerstrip to read/write the EDID data.

A great article covering this topic: Change the display EDID (google translated from German)