Linux 3.x: Flickering when logging into GNOME Shell or Unity

[Paul Menzel]

Am Donnerstag, den 18.10.2012, 18:14 -0400 schrieb Alex Deucher:
> On Wed, Oct 17, 2012 at 4:48 PM, Paul Menzel wrote:
> > Am Mittwoch, den 17.10.2012, 16:25 -0400 schrieb Alex Deucher:
> >> On Wed, Oct 17, 2012 at 11:26 AM, Paul Menzel wrote:
> >
> >> > Am Mittwoch, den 17.10.2012, 16:49 +0200 schrieb Paul Menzel:
> >> >
> >> >> setting up an ASUS M2A-VM after some months with
> >> >>
> >> >>         [    3.178337] [drm] initializing kernel modesetting (RS690 0x1002:0x791E 0x1043:0x826D).
> >> >>
> >> >> logging in into GNOME Shell (GNOME 3) or for testing with Ubuntu 12.04
> >> >> and Unity, the image flickers for a second and then works normally.
> >> >>
> >> >> Turning on debugging
> >> >>
> >> >>         /sys/module/drm/parameters$ echo "0x06" | sudo tee debug
> >> >>         sudo: unable to resolve host granit
> >> >>         0x06
> >> >>
> >> >> before logging in, the following is logged. Looking at the source code,
> >> >> I do not see that this is supposed to be a problem. But maybe you can
> >> >> figure out more.
> >> >>
> >> >>         [  454.896408] [drm:drm_mode_addfb], [FB:41]
> >> >>         [  454.896427] [drm:radeon_crtc_page_flip], flip-ioctl() cur_fbo = ffff880072438400, cur_bbo = ffff880037072400
> >> >
> >> > trying Linux 3.5
> >> >
> >> >         $ dpkg -l linux-image-3.5* | grep ii | tr -s ' ' | cut -d ' ' -f 2-4
> >> >         linux-image-3.5-trunk-amd64 3.5.5-1~experimental.1 amd64
> >> >
> >> > the flickering is still there.
> >>
> >> I don't see anything wrong in the log.  Does the flicker occur at
> >> regular intervals or just at start up?
> >
> > As far as I see, one second after hitting enter in the graphical login
> > manager (LightDM in this case).
> >
> >> I suspect the flicker may be due to your desktop environment probing
> >> for monitors at startup
> >
> > Hmm. Only a VGA monitor is detected and I do not see that issue on
> > different system where I tested GNOME Shell to reproduce this. I have
> > test Unity too again.
> 
> Depends on the system and what connectors they have and whether or not
> they support load detection.

Is there a way to find out? This is an ASUS M2A-VM [1] with a VGA and
DVI connector.

> > Though the probing should be in the logs somehow? But there are not
> > during the time of login.
> >
> >> which causes a flicker if nothing is attached to the analog ports
> >> (VGA, s-video) as that results in a load detection operation to probe
> >> for old monitors without EDIDs or analog TVs.
> >
> > Any hint on how to rule that out? Disable some outputs on the command
> > line or so?
> 
> Depending on what is doing the probing you could try starting bare X
> without a desktop environment.  Or disable the analog outputs you
> aren't using in your xorg.conf.  E.g.,
> 
>   Section "Monitor"
>     Identifier "S-video"
>     Option "Disable" "true"
>   EndSection

I added that to the new file `/etc/X11/xorg.conf.d/99-disable.conf` also
disabling HDMI-0 and DVI-0. Nothing changed though after restarting the
graphical login manager (logging out and back in).


Thanks,

Paul


[1] http://www.asus.com/Motherboards/AMD_AM2/M2AVM/
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