Details On Intel Ivy Bridge Triple Monitor Support

[phoronix]

Phoronix: Details On Intel Ivy Bridge Triple Monitor Support

Patches were made public by Intel yesterday for their Linux graphics driver that enable "Ivy Bridge" hardware to simultaneously drive three monitors. Thanks to Intel's Linux driver being open-source and their OSTC developers doing the hardware enablement work in public, there's some new details about this triple monitor support for the next-generation Ivy Bridge hardware...

http://www.phoronix.com/vr.php?view=OTk3Mw

[Saist]

hmm... even better graphics performance than Sandy Bridge...

so... that's what? They'll finally be able to match a RadeonHD 2600?

I guess that would be a step forward for Intel.

[ChrisXY]

This is old news, but I had the joy of actually trying the triple monitor support on a notebook today.

If you connect two different screens, at boot linux 3.7 and git master from today will flood your terminal with these messages, later it will only occassionally spam one line on your active terminal. I believe you can disable that with dmesg -n 1.

[    7.991435] [drm:intel_crtc_set_config] *ERROR* failed to set mode on [CRTC:7]
[    7.991460] con2fb_init_display: detected unhandled fb_set_par error, error code -22
[    7.991519] [drm:intel_crtc_set_config] *ERROR* failed to set mode on [CRTC:7]
[    7.995437] [drm:intel_crtc_set_config] *ERROR* failed to set mode on [CRTC:7]
[...]
[    8.197793] [drm:intel_crtc_set_config] *ERROR* failed to set mode on [CRTC:7]
[    8.201482] [drm:intel_crtc_set_config] *ERROR* failed to set mode on [CRTC:7]
[    8.205154] [drm:intel_crtc_set_config] *ERROR* failed to set mode on [CRTC:7]
[    8.208810] [drm:intel_crtc_set_config] *ERROR* failed to set mode on [CRTC:7]
[    8.212452] [drm:intel_crtc_set_config] *ERROR* failed to set mode on [CRTC:7]
[    8.216095] [drm:intel_crtc_set_config] *ERROR* failed to set mode on [CRTC:7]

X.org 1.13 will hang with sna and segfault with uxa.

X.org 1.14 will just hang with uxa, with sna it will start. If you try to use xrandr to activate the screen you will get this:

 $ xrandr --output LVDS1 --preferred --output HDMI1 --preferred --output HDMI2 --preferred
xrandr: Configure crtc 2 failed

KDE with compositing enabled will behave erratically, so it's best to turn it off then.

You really do need two of the same screens connected, then it works well.

I believe it would be better to work around the problem with different screen by just duplicating the timings from one and don't care about image stability/clarity on the other one.