every 10s I get "[drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid ..."

[Jonathan Nieder]

Hi dri developers,

Two corrupt-EDID/dmesg-spam puzzles for you.  Seems to be a
regression, though I'm not sure from when.

Stuart Pook writes[1]:

> Every 10 seconds I get the messages at the end of my bug report in
> /var/log/kern.log. My /var/log/kern.log is very big!
[...]
> I have a Benq Product Name FP241W manufactured February 2007 Revision
> B4-125 and used to use the DVI input. The EDID data in the DVI input
> suddenly failed and the my PC would not longer boot. I plugged my PC
> into the HDMI input of the monitor and the machine boots but X does not
> start at the correct resolution. It appears that the EDID data from HMDI
> input does not propose "1920x1200".
[...]
> So once X is running
> I unplug my PC from the HDMI input and plug it into the DVI input. All
> works well, the screen saver makes the screen go into standby mode,
> except that the kernel tells me that the EDID data is not correct every
> 10 seconds.  Is there a way to make it stop?
[...]
>	[drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 34
>	[drm:drm_edid_block_valid] *ERROR* Raw EDID:
>	<3>a1 80 ff ff ff ff ff 00 09 d1 db 76 be 0f 00 00  ...........v....
>	<3>07 11 01 03 80 34 21 78 ea 5a d5 a7 56 4b 9b 24  .....4!x.Z..VK.$
>	<3>13 50 54 bd ef 80 71 4f 81 90 81 80 81 8c a9 40  .PT...qO.......@
>	<3>b3 00 01 01 01 01 28 3c 80 a0 70 b0 23 40 30 20  ......(<..p.#@0 
>	<3>36 00 07 44 21 00 00 1e d5 09 80 a0 20 5e 63 10  6..D!....... ^c.
>	<3>10 60 52 08 78 2d 11 00 00 1a 00 00 00 fd 00 38  .`R.x-.........8
>	<3>4c 1e 53 11 00 0a 20 20 20 20 20 20 00 00 00 fc  L.S...      ....
>	<3>00 42 65 6e 51 20 32 34 31 57 0a 20 20 20 00 dc  .BenQ 241W.   ..

Lisandro Damián Nicanor Pérez Meyer writes[1]:

> With a dual screen setup. Not so long ago (less than a week) both monitors 
> (ViewSonic VG2021wm) were working fine. Somehow the monitor connected to the 
> DVI port started not being detected correctly on boot (wrong edid?). Dmesg 
> shows:
>
> [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 54
> [drm:drm_edid_block_valid] *ERROR* Raw EDID:
> <3>00 ff ff ff ff ff ff 00 5a 63 1e d9 01 01 01 01  ........Zc......
> <3>18 11 01 03 0e 2b 1b 78 2e cf c5 a3 5a 49 a0 25  .....+.x....ZI.%
> <3>12 50 54 bf ef 80 81 80 81 40 71 4f 01 01 01 01  .PT...... at qO....
> <3>01 01 01 01 01 01 21 39 90 30 62 1a 27 40 68 b0  ......!9.0b.'@h.
> <3>36 00 b1 0e 11 00 00 1c 36 00 00 ff 00 51 44 57  6.......6....QDW
> <3>30 37 32 34 36 30 38 36 37 0a 00 00 00 fd 00 32  072460867......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 30 32 31 77 6d 2d 32 0a 20 20 00 64  .VG2021wm-2.  .d
>
> And so I can't go more than 1024x768 on a 1680x1050 capable LCD. As this was 
> working some days ago, there must have been a regression somewhere :-/
[...]
> On Vie 29 Abr 2011 22:08:09 Jonathan Nieder escribió:

>> Thanks.  Could you try the patch from
>> 
>>   https://bugs.freedesktop.org/show_bug.cgi?id=27708#c7
>> 
>> and see what happens when booting with the drm.edid_strict=0 option?
>
> The patch works perfectly, so at least I have a workaround :-) Thank you!
>
> Now the question is why the DVI port gets a corrupt EDID while the VGA port 
> gets it right. Or maybe the code processing the EDID of the DVI port is wrong?
>
> Don't heasitate in contacting me if I can be of any further help.

Known problem?  Ideas?

Jonathan

[1] There are many more details in the original reports, at
http://bugs.debian.org/622993

https://bugs.freedesktop.org/show_bug.cgi?id=31943 looks vaguely
similar.