[Intel-gfx] drm/i915 X crashes on 835GM (IBM R31)

Chris Wilson chris at chris-wilson.co.uk
Tue Oct 22 14:03:32 CEST 2013

On Tue, Oct 22, 2013 at 12:18:54PM +0200, Thomas Richter wrote:
> Hi Chris, hi Daniel,
> >A full drm.debug=6 dmesg, Xorg.0.log and xrandr --verbose would be
> >useful starting point to distangling what is going on. Is this an 830gm
> >or an 845g? google says 830gm, so there should be 2 crtcs available for
> >you to drive the two outputs independently, and we need to find out what
> >is going wrong.
> >-Chris
> >
> You are right, this is a 830GM as far as I know. I'm attaching the
> dmesg.out with drm.debug=255 (hopefully all the data) with an
> external
> monitor attached. I'm also attaching the stderr and stdout of X -
> but it doesn't do much except crashing. If I'm attaching the
> external monitor

Ah, /var/log/Xorg.0.log has greater verbosity than stdout/stderr. I am
just curious where we reject the -intel driver and hence fail to init
the screen.

> later when X is running, I do get a working X, but no picture on the
> external monitor. The xrandr output is also attached.

>From the xrandr, I can see the problem. LVDS1 can be on either CRTC, but
VGA can only be on CRTC-0. At initialisation, LVDS1 is on CRTC-0 and so
prevents the VGA from finding a CRTC.

If you do:
xrandr --output LVDS1 --off
xrandr --output VGA1 --preferred
xrandr --output LVDS1 --preferred

it should work, or more compactly:

xrandr \
  --output VGA1 --preferred --crtc 0 \
  --output LVDS1 --preferred --crtc 1 --primary --left-of VGA1

(adjust primary and position to taste)

Flickering is another problem altogether (who votes for DSPARB?).

Chris Wilson, Intel Open Source Technology Centre

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