Dual screen issues with Radeon X1250 on HP t5730

[Alex Deucher]

On Tue, Jan 20, 2015 at 5:16 AM, Jeffrey Langerak <jeffrey at langerak.it> wrote:
> Hi,
>
>> Does disabling ColorTiling2D or ColorTiling work around the problem? If
>> not, please provide the corresponding Xorg log file.
>
> Disabling the "ColorTiling" option seemed to fix the issue, according to the
> "radeon" manpage this should default to off for this chipset (RS690), but X
> will default it to on. Forcing it to "off" was sufficient and dual screen is
> now working! ColorTiling2D is a safe option for this chip and may be set to
> on.

You may have an outdated man page.  ColorTiling2D has no affect on that asic.

>
> Now that we are discussing this, are there any other options that are useful
> to place in the xorg.conf file to boost the speed of the GPU like
> acceleration enhancements?
>
> One other thing I noticed and is probably because of the VRAM limitation of
> 32MB is that when using the 2 full-HD monitors is that the display sometimes
> shows some interlacing and the monitor connected to the DVI port will loose
> the connection for about a second. Any thougths about that?

Probably underflow to the displays due to memory bandwidth contention
or a problem with the watermark setup on the displays.  Does setting
radeon.disp_priority=2 on the kernel command line in grub help?  I'm
not sure there is enough memory bandwidth to drive two full HD
displays on that asic.

Alex

>
> Someone asked about the VRAM limit, this is fixed because the machine is a
> thin client, the bios does not allow any changes herein, I can only set the
> "vmalloc" parameter when booting the kernel.
>
> Thanks again!
>
> Kind regards,
>
> Jeffrey Langerak
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