DDC: no ddc bus - possible BIOS bug

屋国遥 hyagni at gmail.com
Thu Dec 30 16:19:08 PST 2010

2010/12/31 Alex Deucher <alexdeucher at gmail.com>:
> On Thu, Dec 30, 2010 at 10:25 AM, 屋国遥 <hyagni at gmail.com> wrote:
>> Hello, all.
>> I am trying to make dual-head environment on Mac Pro with Ubuntu
>> 10.10.  My Mac Pro has the Radeon HD 2600 XT graphic card, so I decided
>> to use the radeon driver.
>> Now, I connect two monitors (the same SAMSUNG monitors) and boot the
>> system and X, one display works well, but the other is not recognized.
>> In dmesg, I found out the following error message.
>> I googled the message and found
>> <http://www.mail-archive.com/xorg-driver-ati@lists.x.org/msg16768.html>
>> and <https://bugs.freedesktop.org/show_bug.cgi?id=29255>.  Referring
>> to these posts, I upgraded the kernel to 2.6.36
>> (http://kernel.ubuntu.com/~kernel-ppa/mainline/v2.6.36-maverick/) and
>> also graphic drivers (https://launchpad.net/~xorg-edgers/+archive/ppa).
>> However, the same error is displayed.
>> I am sorry to say that I have no idea how to use Alex's patch to
>> `radeon_atombios.c' because of my poor knowledge of Linux.
>> Is not this change included in the recent kernel or drivers?
>> Because dual-head environment works successfully on Mac, I suspect the
>> monitor or graphic card has no problem.
> You will need a custom patch for your system.  That patch referenced
> in the above thread only applies to evergreen chips.  I suspect apple
> forgot to specify the ddc assignment for one of the heads in their
> vbios and their driver most likely use hardcoded values.  Please send
> me a copy of the vbios from your system, and I'll send you a patch to
> fix it.  Also please attach the pci device and subsystem ids for your
> card (lspci -vnn).  Also, what connectors does your card actually
> have?  Two DVI-I?  Two DVI-I and one TV-out?  It looks like some of
> the encoder mapping might be wrong on your system too.  I can help get
> that fixed up as well.
> To get the 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
> Alex

Hi, Alex.
Thank you for your fast reply.

I understood the situation.

My card has just two DVI-I connectors, no TV-out.
The attached file is vbios.rom.
lspci -vnn result is the following (only the section of VGA controller).

02:00.0 VGA compatible controller [0300]: ATI Technologies Inc RV630
[Radeon HD 2600XT] [1002:9588] (prog-if 00 [VGA controller])
	Subsystem: Apple Computer Inc. Device [106b:00a6]
	Physical Slot: 1
	Flags: bus master, fast devsel, latency 0, IRQ 56
	Memory at 80000000 (64-bit, prefetchable) [size=256M]
	Memory at 90a20000 (64-bit, non-prefetchable) [size=64K]
	I/O ports at 2000 [size=256]
	Expansion ROM at 90a00000 [disabled] [size=128K]
	Capabilities: <access denied>
	Kernel driver in use: radeon
	Kernel modules: radeon

Haruka YAGNI
hyagni at gmail.com
-------------- next part --------------
A non-text attachment was scrubbed...
Name: vbios.rom
Type: application/octet-stream
Size: 62464 bytes
Desc: not available
URL: <http://lists.x.org/archives/xorg-driver-ati/attachments/20101231/0ba1b56f/attachment-0001.obj>

More information about the xorg-driver-ati mailing list