The curious case of ViewSonic's EDID

03.06.2010 21:37

A couple of hours ago I was sitting in front of my desktop computer when I had to step away for a couple of minutes. When I returned, the screensaver had kicked-in and my ViewSonic VG2230wm LCD monitor was in sleep mode. Deep sleep mode it turned out, because I could not wake it up.

After some digging around and fruitless reboots, power cycles and cable reseatings I came to realize that xrandr was simply seeing the DVI-0 connector on my Radeon 4350 as disconnected.

Further, I stumbled upon this report in dmesg:

*ERROR* EDID checksum is invalid, remainder is 111
*ERROR* Raw EDID:
<3>00 ff ff ff ff ff ff 00 5a 63 1e a2 01 01 01 01  ........Zc......
<3>91 11 01 03 80 2f 1e 78 2e d0 05 a3 55 49 9a 27  ...../.x....UI.'
<3>13 50 54 bf ef 80 b3 00 a9 40 95 00 90 40 81 80  .PT......@...@..
<3>81 40 71 4f 31 0a 21 39 90 30 62 1a 27 40 68 b0  .@qO1.!9.0b.'@h.
<3>36 00 da 28 11 00 00 1c 00 00 00 ff 00 XX XX XX  6..(.........XXX
<3>XX XX XX XX XX XX XX XX XX 0a 00 00 00 fd 00 32  XXXXXXXXX......2
<3>4b 1e 52 11 00 0a 20 20 20 20 20 20 00 00 00 fc  K.R...      ....
<3>00 56 47 32 32 33 30 77 6d 2d 45 55 0a 20 00 39  .VG2230wm-EU. .9

radeon 0000:01:00.0: DVI-I-1: EDID invalid.
*ERROR* DVI-I-1: probed a monitor but no|invalid EDID

Did the EDID serial EEPROM just died on me? This story about reprogramming the EDID chip in a TV suggests that at least in some devices these EEPROMs aren't actually write protected. So it might also just been corrupted by a bug in the video driver or something in its vicinity.

OK, doing something like the procedure described in linked article above shouldn't be too hard. But where to find the original, uncorrupted EDID image? ViewSonic helpfully provides software for inspecting EDID, but doesn't include the original data.

Then, while searching for the original EDID image, I stumbled upon this thread about a similar problem. It suggested an amazingly simple solution:

  • Plug in both DVI and VGA cable into video card and monitor,
  • turn on computer and let it boot,
  • shut down computer,
  • unplug VGA cable but leave DVI alone,
  • unplug monitor for 10 seconds,
  • turn on the computer.

I found it hard to believe this voodoo would help, but considering the number of people there that said this helped, I tried it anyway. And it worked!

Interestingly, this is how EDID looks now (changed bytes in bold):

(II) RADEON(0):   00 ff ff ff ff ff ff 00 5a 63 1e a2 01 01 01 01
(II) RADEON(0):   22 11 01 03 80 2f 1e 78 2e d0 05 a3 55 49 9a 27
(II) RADEON(0):   13 50 54 bf ef 80 b3 00 a9 40 95 00 90 40 81 80
(II) RADEON(0):   81 40 71 4f 31 0a 21 39 90 30 62 1a 27 40 68 b0
(II) RADEON(0):   36 00 da 28 11 00 00 1c 00 00 00 ff 00 XX XX XX
(II) RADEON(0):   XX XX XX XX XX XX XX XX XX 0a 00 00 00 fd 00 32
(II) RADEON(0):   4b 1e 52 11 00 0a 20 20 20 20 20 20 00 00 00 fc
(II) RADEON(0):   00 56 47 32 32 33 30 77 6d 2d 45 55 0a 20 00 39

The changed byte represents the week of manufacture according to the EDID standard. 91h is invalid as a week number (at most 36h weeks in a year) and doesn't share any common bits with 22h. This makes it improbable that either some intentional mechanism or a random bit-flip in the hardware would cause this error, so it remains a mystery to me.

Is it just me or you just can't get any work done lately without some random piece of software or hardware going belly up on you?

Posted by Tomaž | Categories: Digital

Comments

So true, that is why we were all supposed to buy iPads ;-)

Posted by Marko

Oh man, thanks for that post. My Viewsonic was driving me insane. The procedure you mentioned here worked just fine for me as well so I'm really happy about that. I must have spent at least a couple of hours just trying to figure out what the problem was before I decided to google it.

And you are so right about saying that these days it always seems one thing or another is going wrong. It seems all I've been doing for the past few weeks is dealing with one problem or another.

Posted by Ray

Incredible but true!

I've been wrestling with a Radeon HD4350 card and a ViewSonic VXwm for the past three days. Don't even know how many times I installed the opensource and ATI drivers and how many different settings I used. At the end it turns out to be the monitor and it works with a voodoo spell!

Thanks for posting your fix man.

Posted by Ziad

OMG, that is some incredible voodoo. This worked for me too. I suppose the restart with both vga and dvi plugged in resets the invalid EDID. Thanks for the solution!!

Posted by Jack

I'm still frustrated after employing this fix. It seemed to work, but after I was away from my computer for an hour it reverted back again.
I'm wishing I had never purchased it.

Posted by Kay Johnson

I had the same issue with DVI cable and ATI driver. I did not have a vga cable handy. However I suffer the same issue with my HTPC HDMI connection and my TV. I solved my HTPC issue with HdmiYo utility that resets the HDMI Link between the monitor and PC. DVI being a digital signal, I was sure this would fix this issue and it did!! I have configured ctrl-space toggle to invoke the utility which resets the device. The utility optionally starts itself on windows startup.

The utility can be downloaded here: http://mymce.wordpress.com/2010/10/24/hdmiyo/.

Posted by sk

1. I verify that this mystery appears only on Viewsonic monitors
2. The solution has to do with the monitor's temp memory , as mentioned. Once this memory is re-initiated (unplug the whole universe from power and plug again in a while)
3. For me , it worked just to change the vga to dvi after a long( 2 mins) monitor power unplug

Thank you very much for your advice. I have fixed this multiples times but now i also understand why.

Posted by TechA

After spending several days reinstalling and updating drivers and changing all kinds of configurations in Windows this fixed the problem with my HP LP3065. After the windows boot logo the screen would go black I would have to unplug/plug in my DVI cable to get the login screen to appear. But simply shutting down windows and unplugging the monitor's power cable for 10 seconds resolved the whole issue. Thank you very much for posting this. I just wonder if the problem was on the monitors side or on the Windows side.

Posted by Walter

Wow, just wow, after about severals days trying to fix this I came up to this solution and boy, it worked like a charm (BenQ XL2411), thanks!

Posted by Shenjiro

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