Comment 16 for bug 547147

Not sure if it is the same bug: due to my wireless (RT2860 of ASUS EeePC 1000H) and mixed mode WPA/WPA2 only working with 2.6.33 kernel (not 2.6.32 with or without backport 2.6.34 driver, 2.6.34 or 2.6.35) I use the 2.6.33.5 kernel from the launchpad kernel PPA (http://kernel.ubuntu.com/~kernel-ppa/mainline/v2.6.33.5-lucid/linux-headers-2.6.33-02063305_2.6.33-02063305_all.deb). With this kernel I see messages on the boot screen before Plymouth takes over, saying:

*ERROR* EDID checksum is invalid

similar messages I find in /var/log/kern.log also backups from the beginning of may, where I had either the original 2.6.32 or the first 2.6.33 kernel installed:

[drm] set up 7M of stolen space
composite sync not supported
[drm] initialized overlay support
[drm:edid_is_valid] *ERROR* EDID checksum is invalid, remainder is 254
[drm:edid_is_valid] *ERROR* Raw EDID:
<3>00 ff ff ff ff ff ff 00 22 64 e9 03 6b 08 00 00 ........"d..k...
<3>1f 12 01 03 80 16 0d 78 0a 86 26 94 57 51 90 27 .......x..&.WQ.'
<3>21 4f 54 00 00 00 01 01 01 01 01 01 01 01 01 01 !OT.............
<3>01 01 01 01 01 01 94 11 00 b0 40 58 19 20 35 23 ..........@X. 5#
<3>45 00 dc 81 00 00 00 19 16 14 00 d8 40 58 26 20 E...........@X&
<3>5d 23 15 04 dc 81 00 00 00 00 00 00 00 fe 00 00 ]#..............
<3>00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fe ................
<3>00 00 00 00 00 00 00 00 00 01 00 00 ff 00 ff 48 ...............H
[drm:edid_is_valid] *ERROR* EDID checksum is invalid, remainder is 35
[drm:edid_is_valid] *ERROR* Raw EDID:
<3>00 ff ff ff ff ff ff 00 ff 64 ff 03 ff 08 ff 00 .........d......
<3>ff 12 ff 03 ff 16 ff ff ff ff ff ff ff ff ff ff ................
<3>ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
<3>ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
<3>ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
<3>ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
<3>ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
<3>ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
fb0: inteldrmfb frame buffer device

Sometimes the log shows only one EDID and different remainders, but same EDID have same remainder. As the display is built in, there should be only one. And it is striking, that xrandr --verbose gives an EDID mostly identical to the first EDID, only differing in byte 125 and 127, where it has 00 instead of ff, and the checksum is 0. So it seems xrandr reports a valid EDID, while libdrm sees a faulty one.

dmesg reports:

dmesg | grep drm
[ 6.386776] [drm] Initialized drm 1.1.0 20060810
[ 6.573893] [drm] set up 7M of stolen space
[ 6.679271] [drm] initialized overlay support
[ 7.099067] [drm:edid_is_valid] *ERROR* EDID checksum is invalid, remainder is 252
[ 7.099087] [drm:edid_is_valid] *ERROR* Raw EDID:
[ 7.200995] [drm:edid_is_valid] *ERROR* EDID checksum is invalid, remainder is 12
[ 7.201036] [drm:edid_is_valid] *ERROR* Raw EDID:
[ 7.211960] fb0: inteldrmfb frame buffer device
[ 7.211984] [drm] Initialized i915 1.6.0 20080730 for 0000:00:02.0 on minor 0

The graphics chipset is an Intel 945GM. lspci gives:

00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller (rev 03)