Comment 6 for bug 1215449

Thanks for your help.

Here's what happens with xrandr:
  $ xrandr --verbose --output HDMI1 --auto --output HDMI2 --auto --output HDMI3 --auto
crtc 0: 1600x1200 60.0 +1600+0 HDMI3"
crtc 1: 1600x1200 60.0 +3200+42 "HDMI2"
crtc 2: 1600x1200 60.0 +0+0 "HDMI1"

xrandr: Configure crtc failed
crtc 0: disable
crtc 1: disable
crtc 2: disable
screen 0: revert
crtc 0: revert
crtc 1: revert
crtc 2: revert

.... and this in Xorg.0.log

[102235.666] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 0 using HDMI3, position (1600, 0), rotation normal
[102235.820] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 1 using HDMI2, position (3200, 42), rotation normal
[103210.958] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 0 using HDMI3, position (1600, 0), rotation normal
[103211.108] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 1 using HDMI2, position (3200, 42), rotation normal
[103511.282] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 0 using HDMI3, position (1600, 0), rotation normal
[103511.436] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 1 using HDMI2, position (3200, 42), rotation normal
[108079.743] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 0 using HDMI3, position (1600, 0), rotation normal
[108079.896] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 1 using HDMI2, position (3200, 42), rotation normal
[108979.952] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 0 using HDMI3, position (1600, 0), rotation normal
[108980.104] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 1 using HDMI2, position (3200, 42), rotation normal
[109280.268] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 0 using HDMI3, position (1600, 0), rotation normal
[109280.420] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 1 using HDMI2, position (3200, 42), rotation normal
[116494.044] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 0 using HDMI3, position (1600, 0), rotation normal
[116494.196] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 1 using HDMI2, position (3200, 42), rotation normal
[116505.236] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 2 using HDMI1, position (0, 0), rotation normal
[116505.238] (EE) intel(0): failed to set mode: Invalid argument
[116505.294] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 0 using HDMI3, position (1600, 0), rotation normal
[116505.448] (II) intel(0): switch to mode 1600x1200@60.0 on pipe 1 using HDMI2, position (3200, 42), rotation normal

I'll try the drm.debug in a moment.