No DVI output on ATI Xpress 200 - reopen

Alex Deucher alexdeucher at
Mon Jul 23 08:02:40 PDT 2012

On Mon, Jul 23, 2012 at 6:06 AM, Przemysław Tomczyk
<tomczyk.przemek at> wrote:
> could it be possible that I'd try to communicate with LCD display thru
> ddc using i2c-dev module to probe how to access it? maybe this would
> help?

You can try accessing the i2c buses exposed by the radeon driver and
seeing which one (if any) has the edid for the DVI port using
i2c_detect or something similar.  Let me know what you find out.


> 2012/7/19 Alex Deucher <alexdeucher at>:
>> On Thu, Jul 19, 2012 at 7:25 AM, Przemysław Tomczyk
>> <tomczyk.przemek at> wrote:
>>> Hi and hello to the list,
>>> Recently I've received workstation with Xpress 200 card, no DVI
>>> output. Kernel is 3.4.4.
>>> DVI output goes blank as soon as KMS kicks in.
>>> Xorg.log mentions no EDID for DVI-0, but forcing edid from file using
>>> drm_kms_helper module didn't help.
>>> Now i'm getting "DVI: Failed to assign ddc bus! Check dmesg for i2c
>>> errors.", bot no i2c errors in dmesg output.
>>> in /sys i c an see nodes for 2 buses:
>>> #cat /sys/devices/pci0000\:00/0000\:00\:01.0/0000\:01\:05.0/i2c-2/name
>>> Radeon i2c bit bus VGA_DDC
>>> # cat /sys/devices/pci0000\:00/0000\:00\:01.0/0000\:01\:05.0/i2c-1/name
>>> Radeon i2c bit bus DVI_DDC
>>> I have bios dump ready to attach on request.
>> Please open a bug:
>> Product: DRI, component: DRM/Radeon
>> and attach your xorg log, dmesg output, and a copy of your vbios.  To
>> get a copy of your vbios:
>> (as root)
>> (use lspci to get the bus id)
>> cd /sys/bus/pci/devices/<pci bus id>
>> echo 1 > rom
>> cat rom > /tmp/vbios.rom
>> echo 0 > rom
>> Thanks!
>> Alex

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