Hi.

I'm experiencing this issue on Fedora kernel, but I tested that upstream kernel behaves the same.

Description of problem:

On my T440s machine I'm experiencing this regression when if I turn off DP connected display, I can never make graphics work again.

Version-Release number of selected component (if applicable): 3.17.6-200.fc20.x86_64

How reproducible: always

Steps to Reproduce: 1. have DP connected display 2. turn it off 3. turn it on

Actual results: No signal in display.

Expected results: There's signal going into display, everything is flooded in colours.

Additional info: With 3.16.4-200.fc20.x86_64 this is working without any issues. I tested with current Linus's git (58628a7831edac5f7a13) and the issue is still there.

00:02.0 0300: 8086:0a16 (rev 0b) (prog-if 00 [VGA controller]) Subsystem: 17aa:220c Flags: bus master, fast devsel, latency 0, IRQ 60 Memory at f0000000 (64-bit, non-prefetchable) [size=4M] Memory at e0000000 (64-bit, prefetchable) [size=256M] I/O ports at 3000 [size=64] Expansion ROM at <unassigned> [disabled] Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit- Capabilities: [d0] Power Management version 2 Capabilities: [a4] PCI Advanced Features Kernel driver in use: i915 Kernel modules: i915

Screen 0: minimum 320 x 200, current 1920 x 1200, maximum 8192 x 8192 eDP-0 connected (normal left inverted right x axis y axis) 1920x1080 60.01 + 1400x1050 59.98 1280x1024 60.02 1280x960 60.00 1024x768 60.00 800x600 60.32 56.25 640x480 59.94 DP-0 disconnected (normal left inverted right x axis y axis) HDMI-0 disconnected (normal left inverted right x axis y axis) DP-1 connected primary 1920x1200+0+0 (normal left inverted right x axis y axis) 518mm x 324mm 1920x1200 59.95*+ 1920x1080 60.00 50.00 59.94 1920x1080i 60.00 50.00 59.94 1600x1200 60.00 1680x1050 59.95 1280x1024 60.02 1440x900 59.89 1280x960 60.00 1280x720 60.00 50.00 59.94 1024x768 60.00 800x600 60.32 720x576 50.00 720x480 60.00 59.94 640x480 60.00 59.94 HDMI-1 disconnected (normal left inverted right x axis y axis)

Please let me know if you need me to provide any other info. I'm eager to test patches.

Thanks!

Jiri