Strange "flicker" in any attempt to manage screen resolution

langriss · 2010-01-13 00:20:21

There is a strange problem happening with X in my laptop (Acer AS1410-8414): whenever any change or even query to the resolution is made, the screen starts "flickering", with Xorg using up almost 100% CPU and mouse/keyboard unusable; going to a VT and get back after some seconds seems to solve the issue. This is annoying because happens twice when starting Gnome (first one when X loads and then after logging in at GDM), and any attempt to manage resolution causes the problem. Just running xrandr with no parameters is enough to start the problem.

Below is an excerpt of /var/log/Xorg.0.log, where a lot of entries keep repeating when the flicker occurs:

(II) intel(0): Printing DDC gathered Modelines:
(II) intel(0): Modeline "1366x768"x0.0   65.50  1366 1390 1406 1406  768 770 774 776 -hsync -vsync (46.6 kHz)
(II) intel(0): EDID vendor "AUO", prod id 8284
(II) intel(0): Printing DDC gathered Modelines:
(II) intel(0): Modeline "1366x768"x0.0   65.50  1366 1390 1406 1406  768 770 774 776 -hsync -vsync (46.6 kHz)
(II) intel(0): EDID vendor "AUO", prod id 8284
(II) intel(0): Printing DDC gathered Modelines:
(II) intel(0): Modeline "1366x768"x0.0   65.50  1366 1390 1406 1406  768 770 774 776 -hsync -vsync (46.6 kHz)
(II) intel(0): EDID vendor "AUO", prod id 8284
(II) intel(0): Printing DDC gathered Modelines:
(II) intel(0): Modeline "1366x768"x0.0   65.50  1366 1390 1406 1406  768 770 774 776 -hsync -vsync (46.6 kHz)
(II) intel(0): EDID vendor "AUO", prod id 8284
(II) intel(0): Printing DDC gathered Modelines:
(II) intel(0): Modeline "1366x768"x0.0   65.50  1366 1390 1406 1406  768 770 774 776 -hsync -vsync (46.6 kHz)
(II) intel(0): EDID vendor "AUO", prod id 8284
(II) intel(0): Printing DDC gathered Modelines:
(II) intel(0): Modeline "1366x768"x0.0   65.50  1366 1390 1406 1406  768 770 774 776 -hsync -vsync (46.6 kHz)
(II) intel(0): EDID vendor "AUO", prod id 8284
(II) intel(0): Printing DDC gathered Modelines:
(II) intel(0): Modeline "1366x768"x0.0   65.50  1366 1390 1406 1406  768 770 774 776 -hsync -vsync (46.6 kHz)
(II) intel(0): EDID vendor "AUO", prod id 8284
(...)

These lines repeat over and over inside the log until I switch to a VT, when the following lines appear:

(II) AIGLX: Suspending AIGLX clients for VT switch
(II) AIGLX: Resuming AIGLX clients after VT switch
(II) intel(0): No memory allocations
(II) intel(0): EDID vendor "AUO", prod id 8284
(II) intel(0): Printing DDC gathered Modelines:
(II) intel(0): Modeline "1366x768"x0.0   65.50  1366 1390 1406 1406  768 770 774 776 -hsync -vsync (46.6 kHz)
(--) SynPS/2 Synaptics TouchPad: touchpad found

I tried searching the forum, but to no avail. Any idea on what's happening?

mwc · 2010-01-16 02:10:13

I have precisely the same problem on an AS1810T. One thing I've noticed is that if I create an xorg.conf which disables all the other outputs the card (thinks it) has, the cycling occurs much more frequently, I conclude from this that the problem is specifically with probing the LCD and not with the presense of the nonexistent HDMI2 and DPI[1-3] outputs.

Xorg.conf:

# vim:ft=xf86conf sts=4 sw=4 ai et
Section "Device"
Identifier "Built-in Intel GS45 Graphics"
Driver "intel"
BusID "PCI:0:2:0"
Option "monitor-LVDS1" "Builtin LCD"
Option "monitor-VGA1" "Disabled Monitor"
Option "monitor-HDMI1" "Disabled Monitor"
Option "monitor-HDMI2" "Disabled Monitor"
Option "monitor-DP1" "Disabled Monitor"
Option "monitor-DP2" "Disabled Monitor"
Option "monitor-DP3" "Disabled Monitor"
EndSection
Section "Monitor"
Identifier "Builtin LCD"
Endsection
Section "Monitor"
Identifier "Disabled Monitor"
Option "Ignore" "true"
EndSection
Section "Screen"
Identifier "Main Display"
Device "Built-in Intel GS45 Graphics"
EndSection
Section "ServerLayout"
Identifier "Default Layout"
Screen "Main Display"
EndSection

Last edited by mwc (2010-01-16 02:10:43)

langriss · 2010-01-16 06:40:14

I managed to find a workaround, but it is kinda brute force... I just renamed /usr/bin/xrandr and the flickering stopped - this suggests that xrandr was the culprit of the flicker. I know that I'm shooting the messenger, but until I find what's really happening with all the excessive LCD probing/flicker I'll just have to live with it. Maybe a new version of Xorg/video driver/kernel may solve this?

mwc · 2010-01-16 07:02:02

I tried setting the modeline for the monitor directly in xorg and disabling DDC in the driver section, but it didn't fix anything. I've also upgraded to xf86-video-intel 2.10 (which I built myself) but it didn't fix anything either. It seems the problem is in the DDX component (xf86-video-intel) since this probe loop doesn't happen when the kernel sets the mode at boot. I'm going to go bitch some more on #intel-gfx and see if anything shakes loose.

yeke · 2010-01-26 08:34:40

I am having the exact same problem on an Acer AS1810T. Closing and opening the lid makes Xorg go to 100%, going to Display in settings, ... everything related to display.
It also happens when I run xrandr, so I just renamed it like suggested, and now everything works.
It might be worth mentioning, but when I run the renamed xrandr, which I called xrandr0, Xorg doesn't go to 100% and everything works fine. When I renamed it back to xrandr, and run it with the original name, it hangs again.

mwc · 2010-03-01 22:29:42

For the sake of those finding this thread in the future, this probably isn't your problem: kernel 2.6.33 fixes this issue for me.

Arch Linux

#1 2010-01-13 00:20:21

Strange "flicker" in any attempt to manage screen resolution

#2 2010-01-16 02:10:13

Re: Strange "flicker" in any attempt to manage screen resolution

#3 2010-01-16 06:40:14

Re: Strange "flicker" in any attempt to manage screen resolution

#4 2010-01-16 07:02:02

Re: Strange "flicker" in any attempt to manage screen resolution

#5 2010-01-26 08:34:40

Re: Strange "flicker" in any attempt to manage screen resolution

#6 2010-03-01 22:29:42

Re: Strange "flicker" in any attempt to manage screen resolution

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