[Bug 99322] [SKL] Flashing black screen with dual monitors

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=99322

--- Comment #23 from Tim Small <tim at buttersideup.com> ---
Have updated to 4.15.0-rc7-drm-tip+ #12 SMP Tue Jan 9 12:46:56 UTC 2018 and the
problem is now back to being very frequent and is following the behaviour in
the first comment again.

Following boot, everything will be fine for a while, then both monitors blank
briefly - in the logs I get:

[16233.854617] [drm:gen8_irq_handler [i915]] hotplug event received, stat
0x00400000, dig 0x10101110, pins 0x00000040
[16233.854746] [drm:intel_hpd_irq_handler [i915]] digital hpd port C - short
[16233.855222] [drm:intel_dp_hpd_pulse [i915]] got hpd irq on port C - short
[16233.857027] [drm:intel_dp_read_dpcd [i915]] DPCD: 12 14 c4 01 01 00 01 40 02
02 06 00 00 00 00
[16233.857941] [drm:intel_dp_check_link_status [i915]] DDI C: channel EQ not
ok, retraining
[16233.859760] [drm:intel_dp_set_signal_levels [i915]] Using signal levels
00000000
[16233.859874] [drm:intel_dp_set_signal_levels [i915]] Using vswing level 0
[16233.859969] [drm:intel_dp_set_signal_levels [i915]] Using pre-emphasis level
0
[16233.860096] [drm:intel_dp_program_link_training_pattern [i915]] Using DP
training pattern TPS1
[16233.860995] [drm:intel_dp_set_signal_levels [i915]] Using signal levels
04000000
[16233.861042] [drm:intel_dp_set_signal_levels [i915]] Using vswing level 1
[16233.861063] [drm:intel_dp_set_signal_levels [i915]] Using pre-emphasis level
0
[16233.861689] [drm:intel_dp_set_signal_levels [i915]] Using signal levels
07000000
[16233.861715] [drm:intel_dp_set_signal_levels [i915]] Using vswing level 2
[16233.861737] [drm:intel_dp_set_signal_levels [i915]] Using pre-emphasis level
0
[16233.862349] [drm:intel_dp_start_link_train [i915]] clock recovery OK
[16233.862378] [drm:intel_dp_program_link_training_pattern [i915]] Using DP
training pattern TPS3
[16233.863848] [drm:intel_dp_set_signal_levels [i915]] Using signal levels
08000000
[16233.863871] [drm:intel_dp_set_signal_levels [i915]] Using vswing level 2
[16233.863908] [drm:intel_dp_set_signal_levels [i915]] Using pre-emphasis level
1
[16233.864840] [drm:intel_dp_set_signal_levels [i915]] Using signal levels
08000000
[16233.864864] [drm:intel_dp_set_signal_levels [i915]] Using vswing level 2
[16233.864886] [drm:intel_dp_set_signal_levels [i915]] Using pre-emphasis level
1
[16233.865773] [drm:intel_dp_start_link_train [i915]] Channel EQ done. DP
Training successful
[16233.865964] [drm:intel_dp_start_link_train [i915]] [CONNECTOR:65:DP-1] Link
Training Passed at Link Rate = 540000, Lane count = 4
[16233.887606] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU
pipe A FIFO underrun

Once that has happened once, then the right-hand screen becomes prone to
blanking for a few seconds at a time, repeatedly, following irregular timings,
but often coming in clusters.  There are no further kernel errors when the
blanks occur.

Sometimes it seems possible to trigger the blanking by repeatedly moving the
mouse cursor onto the secondary screen from the primary screen, but sometimes
it occurs without this, and it's possible that the two are connected.

-- 
You are receiving this mail because:
You are on the CC list for the bug.
You are the QA Contact for the bug.
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/intel-gfx-bugs/attachments/20180110/0958bd5f/attachment-0001.html>