Radeon 9600 XT trouble radeon.hw_i2c

[Patrick Haller]

Hi,

I've got two ViewSonic 930 LCDs attached to the DVI-0 and VGA-0 port of 
a Sapphire Radeon 9600 XT. Using GIT master of xf86-video-ati on 
xorg-1.9.3 RC 2 on Linux kernel 2.6.37 (gentoo).

Experimenting with radeon.hw_i2c=1 caused the DVI-0 LCD to go black 
during boot. To identify the cause of the problem, I exchanged the 
identical panels with the effect that the 2nd LCD also went dead on 
DVI-0. Restarts and operating system switches didn't help.

Eventually, both panels kept working on VGA-0 with initial 1024x768 and 
dmesg showed that the EDIDs of both panels were corrupt.
radeon.hw_i2c=1 seemingly has overwritten substantial parts of the the 
LCDs EDID EEPROM with 0xff. (i2cdump)

To my great relief, I was able to manually (using i2cset and a VP930 
reference EDID block) restore both EDID EEPROMS and got the panels 
working fine again.
I'd not be too fond of retrying the whole procedure in order to ensure 
that hw_i2c really was the culprit.

Have I overlooked documented warning of using hw_i2c on this old board 
or has anyone else experienced such?


Thanks,
Patrick
-------------- next part --------------
A non-text attachment was scrubbed...
Name: patrick_haller.vcf
Type: text/x-vcard
Size: 306 bytes
Desc: not available
URL: <http://lists.x.org/archives/xorg/attachments/20110108/2efe9603/attachment.vcf>