Unsynced TMDS with xf86-video-intel on 945GM

Jacobo Polavieja jacobopolavieja at gmail.com
Wed May 16 21:46:10 PDT 2007

Alex Deucher escribió:
> On 5/16/07, René Rebe <rene at exactcode.de> wrote:
>> On Wednesday 16 May 2007 21:36:22 Keith Packard wrote:
>>> On Mon, 2007-05-14 at 09:18 +0200, René Rebe wrote:
>>>> However often (like about 80% of the X starts) I get flickering and rolling thru
>>>> pixel trash on the external display. It "looks" like there is some sync (or so)
>>>> missing or imprecise, as it's the actual desktop pixel content flushing and
>>>> shuffling by.
>>>> This can be fixed by re-enabling the LVDS and disabling it again:
>>> Sounds like the mode programming has some stability issues; the
>>> registers in the chip must be programmed in the right sequence and with
>>> the right delays between various steps in the process. Failing to wait
>>> long enough for a PLL to lock can result in 'bad' behaviour like this.
>>> About the only way to debug this is to add delays at various points in
>>> the mode setting operation, most likely the CRTC timing programming,
>>> although it's possible that the SDVO programming is broken instead.
>>> One thing to always try is the latest development version of the X
>>> server and intel driver; there are a few minor fixes which may be
>>> related. Plus, patches you come up with won't need to be ported forward.
>> Do you have an explanation why the distortion on the TMDS-1
>> is mostly disappearing when I rotate the 3D desktop cube?
>> I would rather expect the "mis-programmed" TMDS output
>> to have a static noise than changing with 3D engine load, ... ?
> Probably memory controller contention.  Some cheap radeon cards with
> slow memory have the same problem when 3D is active.  The memory
> controller can't service both clients (crtc and 3D) fast enough.  You
> may try reducing the timing on your panel or, if you can, bump the
> crtc's priority in the memory controller.  This will come at the
> expense of 3D performance.
> Alex
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> xorg at lists.freedesktop.org
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I'm a completely newbie in this area but... with the same problem as
René, my glxinfo reports this:

cobo at mortadelo ~ $ glxinfo | grep direct
libGL error: open DRM failed (Operation not permitted)
libGL error: reverting to (slow) indirect rendering
direct rendering: No
cobo at mortadelo ~ $

I assume I don't have 3d acceleration right now, am I wrong? I don't
know if this might help to stretch the problem.


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