[SOLVED] bad EDID checksum for laptop LCD display

[lolo44]

Hi !

After the MGA2 upgrade I get a warning during boot phase.

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Jun  1 18:40:16 asterix kernel: [    1.504836] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 110
Jun  1 18:40:16 asterix kernel: [    1.504847] Raw EDID:
Jun  1 18:40:16 asterix kernel: [    1.504851]          f0 57 06 04 32 0c 00 00 ff 01 36 00 ff 0c 00 01
Jun  1 18:40:16 asterix kernel: [    1.504856]          01 74 40 74 40 12 00 04 0b 48 00 01 01 05 01 00
Jun  1 18:40:16 asterix kernel: [    1.504861]          00 aa 0a e4 08 10 09 10 00 0d 02 e0 01 e3 01 02
Jun  1 18:40:16 asterix kernel: [    1.504866]          ff ff ff ff d3 00 ff ff ff ff d9 00 ff ff ff ff
Jun  1 18:40:16 asterix kernel: [    1.504871]          d7 00 ff ff ff ff dd 00 ff ff ff ff de 00 ff ff
Jun  1 18:40:16 asterix kernel: [    1.504876]          ff ff db 00 ff ff ff ff df 00 ff ff ff ff ff ff
Jun  1 18:40:16 asterix kernel: [    1.504881]          ff ff ff ff ff ff ff ff c8 00 c1 00 c2 00 c4 00
Jun  1 18:40:16 asterix kernel: [    1.504885]          d8 00 d1 00 d2 00 d4 00 ff ff ff ff ff ff ff ff
Jun  1 18:40:16 asterix kernel: [    1.504891] [drm:radeon_atombios_get_lvds_info] *ERROR* Bad LCD record 87


System is performing fine, so I'm not so worried, but just wonder what this warning means. It looks like it appeared also in MGA1 but with much less verbose stuff . this was looking like :

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Apr 30 08:17:23 asterix kernel: [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 93
Apr 30 08:17:23 asterix kernel: [drm:drm_edid_block_valid] *ERROR* Raw EDID:
Apr 30 08:17:23 asterix kernel:
Apr 30 08:17:23 asterix kernel: [drm:radeon_atombios_get_lvds_info] *ERROR* Bad LCD record 87


I run on an ACER 5512WMLI, with an embedded radeon mobile x700 (well I think it's an x700, the sticker is not readable any more )

Screen is doing well, so I don't mind the warning yet... but I read on some site found by googling that it could indicate either issue with the LCD or just bad work from the laptop builder (acer)... just would like to know

BTW, GREAT WORK MGA TEAM. MGA2 IS A VERY GOOD DISTRO !
(I guess this is what should have been mandriva 2012, which was a nightmare instead (at lest for me ) )

Rgds
Laurent

[doktor5000]

Seems the display identification data is messed up somehow or it is trying to read display identification data from an non-existent display. Maybe you want to have a look at http://en.wikipedia.org/wiki/Extended_d ... ation_data for some background information. If the screen runs at the correct resolution, and displays properly, you can just forget about it.

Also please use a more meaningful thread title, maybe change it in the first post to "bad EDID checksum for laptop LCD display" or so, and please mark it [SOLVED] by prefixing the title with that if everything display-wise is fine.

[lolo44]

Hi, thanks for your answer.

Sure the LCD is working so no real worry...
Just questionning why radeon / drm module is complaining..

I ran monitor-get-edid :

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00 FF FF FF  FF FF FF 00  06 AF 74 21  00 00 00 00  01 0F 01 03  80 21 15 78  ..........t!.........!.x
0A 1C F5 97  58 50 8E 27  27 50 54 00  00 00 01 01  01 01 01 01  01 01 01 01  ....XP.''PT.............
01 01 01 01  01 01 C7 1B  00 A0 50 20  17 30 30 20  36 00 4B CF  10 00 00 18  ..........P .00 6.K.....
00 00 00 0F  00 00 00 00  00 00 00 00  00 00 00 00  00 20 00 00  00 FE 00 41  ................. .....A
55 4F 0A 20  20 20 20 20  20 20 20 20  00 00 00 FE  00 42 31 35  34 45 57 30  UO.         .....B154EW0
32 20 56 31  20 0A 00 AA                                                      2 V1 ...

This doesn't look like what the module is reporting at boot time...
But it looks like a valid EDID...

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EISA ID: AUO2174
EDID version: 1.3
EDID extension blocks: 0
Screen size: 33.1 cm x 20.7 cm (15.37 inches, aspect ratio 16/10 = 1.60)
Gamma: 2.2
Digital signal

        # Monitor preferred modeline (60.0 Hz vsync, 49.4 kHz hsync, ratio 16/10, 98 dpi)
        ModeLine "1280x800" 71.11 1280 1328 1360 1440 800 803 809 823 -hsync -vsync


BTW, as said, picture is OK on this screen ...

Best Regards.

[doktor5000]

Well, without knowing more about your setup or without being able to take a closer look myself, i can't tell you. But you can just google for "*ERROR* EDID checksum is invalid" and you will get endless results, mostly when using radeon drivers, as they try to query non-existent displays or other such problems.
If the picture is OK, then i'd say don't care about it.

There's one golden rule i've learned over the years: If there's an error message, as critical as it may sound, but there's no corresponding error, then just ignore it (after some investigation about that problem and it's context). This is what you did, and there seems to be no problem, so please remove the question mark from the title of the first post as the thread is done. Thanks in advance.