https://bugzilla.novell.com/show_bug.cgi?id=680085
https://bugzilla.novell.com/show_bug.cgi?id=680085#c1
--- Comment #1 from Joschi Brauchle 2011-03-16 10:35:20 UTC ---
Additional info:
The grafics card has a DMS-59 connector and I use a "DMS-59 to dual DVI"
adapter cable to connect two identical monitors. I was running this setup
successfully with OpenSUSE 11.3, no problems at all. We have about 50 identical
machines running this setup on 11.1, also no problems.
My problem seems to be very similar to the one described on the following
kernel-commit, except that I am not using "DisplayPort to duallink DVI" but
"DMS-59 to dual DVI":
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commit 0f37a87fae33bbca1e2ff289330c2f4ba93b5064
Author: David Flynn
Date: Wed Dec 8 16:10:21 2010 +0000
drm/i915/dp: Fix I2C/EDID handling with active DisplayPort to DVI converter
commit 8316f33766a82907c694267ff911e45e256f09f9 upstream.
The DisplayPort standard (1.1a) states that:
The I2C-over-AUX Reply field is valid only when Native AUX CH Reply
field is AUX_ACK (00). When Native AUX CH Reply field is not 00, then,
I2C-over-AUX Reply field must be 00 and be ignored.
This fixes broken EDID reading when using an active DisplayPort to
duallink DVI converter. If the AUX CH replier chooses to defer the
transaction, a short read occurs and erroneous data is returned as
the i2c reply due to a lack of length checking and failure to check
for AUX ACK.
As a result, broken EDIDs can look like:
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
00: bc bc bc ff bc bc bc ff bc bc bc ac bc bc bc 45 ???.???.???????E
10: bc bc bc 10 bc bc bc 34 bc bc bc ee bc bc bc 4c ???????4???????L
20: bc bc bc 50 bc bc bc 00 bc bc bc 40 bc bc bc 00 ???P???.???@???.
30: bc bc bc 01 bc bc bc 01 bc bc bc a0 bc bc bc 40 ???????????????@
40: bc bc bc 00 bc bc bc 00 bc bc bc 00 bc bc bc 55 ???.???.???.???U
50: bc bc bc 35 bc bc bc 31 bc bc bc 20 bc bc bc fc ???5???1??? ????
60: bc bc bc 4c bc bc bc 34 bc bc bc 46 bc bc bc 00 ???L???4???F???.
70: bc bc bc 38 bc bc bc 11 bc bc bc 20 bc bc bc 20 ???8??????? ???
80: bc bc bc ff bc bc bc ff bc bc bc ff bc bc bc ff ???.???.???.???.
...
which can lead to:
[drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder
[drm:drm_edid_block_valid] *ERROR* Raw EDID:
<3>30 30 30 30 30 30 30 32 38 32 30 32 63 63 31 61 000000028202cc1a
<3>28 00 02 8c 00 00 00 00 18 00 00 00 00 00 00 00 (...............
<3>20 4c 61 73 74 20 62 65 61 63 6f 6e 3a 20 33 32 Last beacon: 32
<3>32 30 6d 73 20 61 67 6f 46 00 05 8c 00 00 00 00 20ms agoF.......
<3>36 00 00 00 00 00 00 00 00 0c 57 69 2d 46 69 20 6.........Wi-Fi
<3>52 6f 75 74 65 72 01 08 82 84 8b 96 24 30 48 6c Router......$0Hl
<3>03 01 01 06 02 00 00 2a 01 00 2f 01 00 32 04 0c .......*../..2..
<3>12 18 60 dd 09 00 10 18 02 00 00 01 00 00 18 00 ..`.............
Signed-off-by: David Flynn
[ickle: fix up some surrounding checkpatch warnings]
Signed-off-by: Chris Wilson
Signed-off-by: Greg Kroah-Hartman
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