Re: [Intel HD 4400] strongly irritating artefacts on 2560x1440 laptop display

[Chris Wilson <chris@chris-wilson.co.uk>]

On Tue, Jan 27, 2015 at 10:49:43PM +0100, Martin Wilck wrote:
> Dear list members,
> 
> I suffer from highly disturbing artefacts with the Intel HD 4400 chip
> set on thw 2560x1440 display (Sharp LQ133T1JW19) of my Fujitsu Lifebook
> S904. The effects are hard to describe, therefore I have uploaded a
> video to
> https://www.dropbox.com/sh/9wh0nzvp0w1phxz/AAAsvAqHN8ApXzor58FmGbwLa?dl=0.
>  I can distinguish 2 effects that are possibly related to each other:

[snip]
 
> 1.) is observed only under GNOME, but I see 2.) on KDE and LXDE, too. I
> also tried various distributions. Most of my experiments have been done
> on OpenSUSE 13.2, kernel-vanilla-3.19.rc5, xorg 7.6_1.16.1-5.1, intel
> 2.99.916, libdrm_intel1-2.4.58-1.1, Mesa 10.3.0-91.3.2. But I see the
> artefacts also on Fedora 21 and Ubuntu 14.04.
> 
> As a matter of fact, I tried the modesetting driver and even fbdev and
> observed similar effects, too. Thus i915 may actually not be the culprit
> here, but could I figure no other place to ask for help than this
> mailing list.

From watching the video, and your comments here, it is clear this is not
a driver bug (neither in the ddx nor opengl compositor). That leaves us
with hardware misconfiguration, aka kernel bug. Some of the artefacts
could be a display underrun. It would be good to check a drm.debug=0xe
dmesg for any warnings (and the info itself will be useful). Another
thing worth playing with is i915.enable_fbc=1 (though that is really
just swapping one problem with another).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
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