Hi, I've seen various threads about this, but never a solution. I have a workaround.
The problem: machine boots fine, shows KDM perfectly. However, after login, the screen is black, but with a mouse cursor visible. You can also do Alt-F2 and run programs normally, although they initially appear scrunched up in the top left corner.
The reason: The problem comes from the i915 driver in the kernel. It doesn't seem to be able to detect the LVDS as connected for some reason, so it returns "connection unknown" to X. If you look at the output of "xrandr" it reads:
Screen 0: minimum 320 x 200, current 1024 x 768, maximum 2048 x 2048
VGA1 unknown connection (normal left inverted right x axis y axis)
1360x768 59.8
1024x768 60.0
800x600 72.2 75.0 60.3
640x480 72.8 75.0 59.9
LVDS1 unknown connection 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
1024x768 60.0*+ 85.0 75.0 70.1 60.0
832x624 74.6
800x600 85.1 72.2 75.0 60.3 56.2
640x480 85.0 72.8 75.0 59.9
720x400 85.0
640x400 85.1
640x350 85.1
Note the "unknown connection" there.
The workaround: I have manually rebuilt the xserver-xorg-video-intel package and hacked it so it thinks the LVDS is always connected. This is done by editing src/drmmode_display.c about line 631 to something like:
if (drmmode_output->output_id == 6)
status = XF86OutputStatusConnected;
else
status = XF86OutputStatusUnknown;
(output 6 being the LVDS).
An alternate method would be to hack the i915 driver in the kernel in file drivers/gpu/drm/i915/intel_crt.c/intel_crt_detect() so that it returns connector_status_connected for the LVDS port. The proper way would be to change the code in there so it has some way to properly detect the connection status.
I can't really develop this any further as I don't have constant access to this laptop (its my mum's old one
, but thought I'd report this in case its useful to someone.
The problem: machine boots fine, shows KDM perfectly. However, after login, the screen is black, but with a mouse cursor visible. You can also do Alt-F2 and run programs normally, although they initially appear scrunched up in the top left corner.
The reason: The problem comes from the i915 driver in the kernel. It doesn't seem to be able to detect the LVDS as connected for some reason, so it returns "connection unknown" to X. If you look at the output of "xrandr" it reads:
Screen 0: minimum 320 x 200, current 1024 x 768, maximum 2048 x 2048
VGA1 unknown connection (normal left inverted right x axis y axis)
1360x768 59.8
1024x768 60.0
800x600 72.2 75.0 60.3
640x480 72.8 75.0 59.9
LVDS1 unknown connection 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
1024x768 60.0*+ 85.0 75.0 70.1 60.0
832x624 74.6
800x600 85.1 72.2 75.0 60.3 56.2
640x480 85.0 72.8 75.0 59.9
720x400 85.0
640x400 85.1
640x350 85.1
Note the "unknown connection" there.
The workaround: I have manually rebuilt the xserver-xorg-video-intel package and hacked it so it thinks the LVDS is always connected. This is done by editing src/drmmode_display.c about line 631 to something like:
if (drmmode_output->output_id == 6)
status = XF86OutputStatusConnected;
else
status = XF86OutputStatusUnknown;
(output 6 being the LVDS).
An alternate method would be to hack the i915 driver in the kernel in file drivers/gpu/drm/i915/intel_crt.c/intel_crt_detect() so that it returns connector_status_connected for the LVDS port. The proper way would be to change the code in there so it has some way to properly detect the connection status.
I can't really develop this any further as I don't have constant access to this laptop (its my mum's old one
, but thought I'd report this in case its useful to someone.