[drm:intel_set_cpu_fifo_underrun_reporting]

[Petko Manolov]

	Hello guys,

Running xorg on my Lenovo Yoga 2 Pro (MY2013) on recent kernels turn into a 
major PITA.  After a couple of minutes the screen starts to flicker and only 
killing xorg or reboot fixes the problem.  This is what i typically see in 
dmesg:


[    0.000000] microcode: microcode updated early to revision 0x1d, date = 2015-08-13
[    0.000000] Linux version 4.7.0-rc3 (petkan at yoga) (gcc version 6.1.1 20160519 (Debian 6.1.1-4) ) #5 SMP Mon Jun 13 12:41:31 EEST 2016
[    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.7.0-rc3 root=/dev/sda1 ro quiet
...
[    0.104213] smpboot: CPU0: Intel(R) Core(TM) i7-4500U CPU @ 1.80GHz (family: 0x6, model: 0x45, stepping: 0x1)
...
[    1.033691] [drm] Initialized drm 1.1.0 20060810
[    1.034106] [drm] Memory usable by graphics device = 2048M
[    1.034108] [drm] Replacing VGA console driver
[    1.040787] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[    1.040788] [drm] Driver supports precise vblank timestamp query.
[    1.066820] [drm] Initialized i915 1.6.0 20160425 for 0000:00:02.0 on minor 0
[    1.231007] fbcon: inteldrmfb (fb0) is primary device
[    2.524538] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device
...
[   92.825302] [drm:intel_set_cpu_fifo_underrun_reporting] *ERROR* uncleared fifo underrun on pipe A
[   92.825312] [drm:ironlake_irq_handler] *ERROR* CPU pipe A FIFO underrun


This is going on for all v4.6 kernel releases as well as v4.7-rcX.  Older, v4.4 
and v4.5, kernels are running fine.  I'm using Debian testing updated to 
2016-06-13.

I'd be happy to help with testing so please let me know if there's anything i 
can do for you.


cheers,
Petko