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

[Thomas Richter]

Daniel, others,

last Friday, I tried drm-intel-nightly on an IBM R31 Thinkpad. This also 
comes with a 835GM chipset (same as the Fujitsu), but the
display is connected via LVDS and not via the NS2501 DVO.

*) Panning also causes the flicker we know already. Interestingly, 
kernel 3.2.0-4 *does not* cause this flicker, it only flickers on the 
external
screen, but not internally.

Is there any way to read the i915 registers from the working 3.2.0-4 
panning and compare that to what the drm-nightly kernel installs?
Something must be different.

*) If I connect an external monitor *before* turning the machine on, X 
creates a segfault. On this machine, no Xorg.conf exists and it is up to 
X to
configure the screens correctly:


X.Org X Server 1.12.4
Release Date: 2012-08-27
X Protocol Version 11, Revision 0
Build Operating System: Linux 2.6.32-5-686-bigmem i686 Debian
Current Operating System: Linux pike 3.12.0-rc5+ #1 SMP Fri Oct 18 
19:44:00 CEST 2013 i686
Kernel command line: BOOT_IMAGE=/boot/vmlinuz-3.12.0-rc5+ 
root=UUID=b82e565b-91ce-41aa-bb56-7e7a7aabc436 ro single
Build Date: 17 April 2013  11:13:16AM
xorg-server 2:1.12.4-6 (Julien Cristau <jcristau at debian.org>)
Current version of pixman: 0.26.0
     Before reporting problems, check http://wiki.x.org
     to make sure that you have the latest version.
Markers: (--) probed, (**) from config file, (==) default setting,
     (++) from command line, (!!) notice, (II) informational,
     (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Mon Oct 21 10:02:04 2013
(==) Using system config directory "/usr/share/X11/xorg.conf.d"

Fatal server error:
AddScreen/ScreenInit failed for driver 0


Please consult the The X.Org Foundation support
      at http://wiki.x.org
  for help.
Please also check the log file at "/var/log/Xorg.0.log" for additional 
information.


Backtrace:
0: X (xorg_backtrace+0x49) [0xb7791769]
1: X (0xb7614000+0x181186) [0xb7795186]
2: (vdso) (__kernel_rt_sigreturn+0x0) [0xb75f540c]
3: X (0xb7614000+0x90d2d) [0xb76a4d2d]
4: X (AbortDDX+0x7d) [0xb76919ed]
5: X (0xb7614000+0x188cb1) [0xb779ccb1]
6: X (0xb7614000+0x188dd5) [0xb779cdd5]
7: X (InitOutput+0xf09) [0xb7693bf9]
8: X (0xb7614000+0x29cc6) [0xb763dcc6]
9: /lib/i386-linux-gnu/i686/cmov/libc.so.6 (__libc_start_main+0xe6) 
[0xb72abe46]
10: X (0xb7614000+0x2a1e9) [0xb763e1e9]

Segmentation fault at address 0x84

Then, both screens go black and I can only reboot the machine.

*) If I connect the external monitor *after* the kernel loaded the i915 
module, X works, but I get no display on the external monitor:

xrandr finds the monitor, though:

Screen 0: minimum 320 x 200, current 1024 x 768, maximum 2048 x 2048
LVDS1 connected 1024x768+0+0 (normal left inverted right x axis y axis) 
0mm x 0mm
    1024x768       60.0*
    800x600        60.3     56.2
    848x480        60.0
    640x480        59.9     59.9
VGA1 connected (normal left inverted right x axis y axis)
    1280x1024      60.0 +   75.0
    1280x960       60.0
    1152x864       75.0
    1024x768       75.1     70.1     60.0
    832x624        74.6
    800x600        72.2     75.0     60.3
    640x480        75.0     72.8     66.7     60.0
    720x400        70.1

but trying to enable it with any type of command (e.g. xrandr --output 
VGA1 --auto or xrandr --output VGA1 --mode 1280x1024) just returns an
error:

xrandr: cannot find crtc for output VGA1

I'm not sure what xrandr is trying to say here.

Greetings,
     Thomas