Comment 8 for bug 1597267

I can confirm that linux-image 4.7.0-994-generic_4.7.0-994.201607052202 from http://kernel.ubuntu.com/~kernel-ppa/mainline/drm-intel-nightly/2016-07-06/ behaves much better.

DP hotplug/unplug behaves correctly across text console, VT switch to lightdm and login into Unity. There's still some WARNs in dmesg (attached) when connecting the external DP monitor, but nothing crashes, and my 4k desktop appears to function correctly:

   [drm:skl_set_cdclk [i915]] *ERROR* failed to inform PCU about cdclk change

    WARNING: CPU: 1 PID: 929 at /home/kernel/COD/linux/drivers/gpu/drm/drm_irq.c:1218 drm_wait_one_vblank+0x16f/0x1b0 [drm]
    vblank not available on crtc 0, ret=-22

    [drm:gen8_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun

Confirmed to still crash with http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.7-rc6-yakkety/