[Nouveau] [Bug 24820] [nv15] Vertical screen corruption in X when KMS is enabled

[bugzilla-daemon at freedesktop.org]

http://bugs.freedesktop.org/show_bug.cgi?id=24820





--- Comment #26 from Francisco Jerez <currojerez at riseup.net>  2009-11-28 06:16:34 PST ---
(In reply to comment #25)
> A new friday - a new status report:
> 
> (In reply to comment #23)
> > last patch but this one should fix it.
> > 
> 
> I tried it with arb_rewrite2.patch and also with
> 
> [PATCH 1/3] drm/nouveau: Update the CRTC arbitration parameters on FB depth
> switch
> [PATCH 2/3] drm/nouveau: Clean up the arbitration parameters calculation code.
> [PATCHv2 3/3] drm/nv10-nv20: CRTC arbitration code rewrite.
> 
> X works but console has flickering artifacts with both.
> (see http://www.freeimagehosting.net/uploads/0f34a8e515.jpg)
> 

It seems your FIFOs are underflowing because of some unknown source of latency.
If you have applied the patch series I sent to the mailing list,
nouveau_calc.c:191 will read:

>         fifo->lwm = min_lwm + 5 * (max_lwm - min_lwm) / 100; /* Empirical. */

That "5" is enough for all the cards I have, but you'll need a higher value,
probably something within [5,40] (don't bother to find a very accurate lower
bound, a +/-5 estimate would be fine).

> (In reply to comment #24)
> >> With a Snapshot via KSnapshot I can see the artifacts, too. (If visible on
> >> "normal" screen at time when "KSnapshotting").
> >> 
> >
> >Does it go away if you set this Section "Device" option in your xorg.conf?
> >> Option "EXANoComposite" "on"
> 
> Yes, but there are other artifacts: E. g. bottom left and bottom right
> "Position" line or "Gamma" with corrupted last "a" and "Mehrere Monitore" with
> corrupted last "e". 
> (see http://www.freeimagehosting.net/uploads/d94750f7aa.png)
> 

The recent changes in the acceleration code your card uses may be the cause of
this. You could try going back to the DDX commit 5587f40, keeping
EXANoComposite set (note that you'll also have to downgrade libdrm, I think
83a35b6 is old enough).

> Do you need a current dmesg?
> 

No, unless you've seen something suspicious (e.g. PGRAPH errors).


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