Created attachment 123650 [details]
dmesg after the black screen, when is not preceded by another *ERROR* message

I have the following issue on my Asus X751MJ laptop, with Linux kernels 4.5.0, 4.5.1 and 4.6-rc6 (does not happen on 4.4.0): at random moments the screen goes black (that is, the backlight gets turned off) and only goes unblack when I move a mouse attached to the laptop or touch the touchpad; this is not a usual pover-saving thing because it usually occurs when I switch between workspaces (I use i3wm). With 4.5.0 and 4.5.1 kernels a reliable way to reproduce it is to open two workspaces and run

    while true; do i3-msg workspace back_and_forth >/dev/null; done

In a few seconds the screen will go black; with 4.6-rc6 kernel the script does not reproduce the issue, and it generally occurs rarer, but still does.

The same thing happens if I run

    xset dpms force off

(but in this case it also goes unblack if I press a key).

When it goes black at the first time after the boot or a suspend, the following lines appear in dmesg:

[drm:valleyview_pipestat_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun

Sometimes it is preceded by the following line:

[drm:intel_set_cpu_fifo_underrun_reporting [i915]] *ERROR* pipe A underrun

The laptop has hybrid graphics, and Intel card plus an NVIDIA one. Initially nouveau was installed, then I tried installing the proprietary NVIDIA driver, but that did not help. Now I removed it, configured X11 to use the Intel card only and even blacklisted the nouveau module, but I didn't help either.