Kernel Bug Tracker – Bug 16149
VGA display is off: blame commit "drm/i915: Don't enable pipe/plane/VCO early (wait for DPMS on)."
Last modified: 2010-06-09 08:41:14 UTC
This commit cfecde435dda78248d6fcdc424bed68d5db6be0b "drm/i915: Don't enable pipe/plane/VCO early (wait for DPMS on)" causes the display of my primary monitor to remain off.
00:02.1 Display controller: Intel Corporation 82G35 Express Integrated Graphics Controller (rev 03)
Main screen is VGA1, and a secondary screen is DVI1, and usually off (note: different screen resolutions).
In 2.6.34 (and before): kernel boots, VGA1 (and DVI1) displays the kernel and init.d messanges, than kdm starts X.
In early post 2.6.34 tree: kernel boots, screen go off (monitor show a "no signal" warning), but when kdm is started, it will display correctly the login screen.
After the commit cfecde435dda78248d6fcdc424bed68d5db6be0b: kernel boots, screen go off, and X starts but without displaying anythings in VGA1. Also after playing with xrandr.
[Note: sometime also on earlier kernel, when screen after screen going to suspend, sometime VGA1 monitor warn about wrong signals (frequency). But in this case xrandr off and on solve the problem.]
oops: correct kernel version 2.6.35-rc1
Also affected by the bug. 2.6.35-rc2
I have confirmed that reverting cfecde435dda78248d6fcdc424bed68d5db6be0b fixes this particular bug and gives me a working display on 2.6.35-rc2.
setting CONFIG_FRAMEBUFFER_CONSOLE_DETECT_PRIMARY also solve this (and additionally it show the console output before starting X),
But I'm confused. If system loads an other fb (see below my list), why:
#1 why Monitor booting the kernel say "No signal" (thus it detect the right video card).
#2 why starting X, without the above commit, the video is show at right resolution (so the fb is correct).
additional info of my configuration:
X.Org X Server 1.7.7
cate@cateee ~/kernel/linux-2.6$ grep FB .config | grep -v '#'
*** This bug has been marked as a duplicate of bug 16163 ***