Problems w/Sandy Bridge & 27" monitor

Chun-Yu Shei
2012-08-15T22:45:35Z

Hi,

I recently upgraded to a 27" monitor (2560x1440) from a 23" one
(1920x1080), and had to switch to Windows because the new monitor is
unusable in Linux. Today, about a month later, I decided to give Linux
another try, since there have been several updates to the Intel graphics
driver since then.

Unfortunately, it seems that it's still unusable with xf86-video-intel
2.20.3 -- after a little while, the video signal to the 27" monitor
completely stops, and it goes into power saving mode. I'm running dual
monitors with the old 23", and that one continues running fine when this
happens. This happens on my ThinkPad X220 (i5-2540M). The 27" is
connected via DisplayPort, and the 23" via DVI. SNA is enabled, if it
makes any difference (I haven't tried turning it off, but I probably
should). This is the biggest problem I'm facing when it comes to Linux
support.

I also gave the new "TearFree" option a try, and while it does a great
job of eliminating tearing, it makes the two monitors become mirrors of
each other for some reason. If I take a screenshot with the GNOME tool,
the screenshot comes out as expected (unmirrored), but the video output
on the two monitors is mirrored in reality. Disabling "TearFree" fixes
this.

Also, when I'm using the ThinkPad's built-in display, it sometimes turns
off for no apparent reason, although it's not too big of a deal since a
suspend/resume cycle seems to fix things (and I haven't used 2.20.3 long
enough to experience this yet).

Any ideas/things I can do to help track these issues down?

Thanks,
Chun-Yu