[Bug 94605] Flashing black screen ([drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=94605

Mauro Santos <registo.mailling at gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |registo.mailling at gmail.com

--- Comment #32 from Mauro Santos <registo.mailling at gmail.com> ---
I believe I'm also seeing this problem, I haven't tried the drm-intel-nightly
branch but I wanted to add a data point that might be useful.

I'm running Arch linux on a Lenovo E560 with an I7-6500U, current kernel
version is 4.6.4.

I have not experienced this problem until I have done some tuning(*) to the
system in order to get deeper package c-states. Before the cpu would not go
lower than PC2, currently the cpu is able to go down to PC7 and according to
powertop there is no PC8~PC10 residency.

Since doing the changes I've seen the following messages in dmesg:
[drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO
underrun
[drm:intel_pipe_update_end [i915]] *ERROR* Atomic update failure on pipe A
(start=414495 end=414496) time 173 us, min 1073, max 1079, scanline start 1069,
end 1081
[drm:intel_pipe_update_end [i915]] *ERROR* Atomic update failure on pipe A
(start=38859 end=38860) time 410 us, min 1073, max 1079, scanline start 1063,
end 1090

The first message seems to be associated with the first flicker, but I've seen
the screen flicker without any new messages being written to dmesg.

I have not noticed any reliable way to trigger this problem, it just happens at
random times.

(*) I have enabled sata alpm (echo min_power >
/sys/class/scsi_host/host{0,1}/link_power_management_policy) which, according
to powertop, allows the cpu to get into PC6, and I have further enabled usb
autosuspend for a device that was preventing the cpu from getting into PC7.

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