<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - [SKL] Flashing black screen with dual monitors" href="https://bugs.freedesktop.org/show_bug.cgi?id=99322#c23">Comment # 23</a> on <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - [SKL] Flashing black screen with dual monitors" href="https://bugs.freedesktop.org/show_bug.cgi?id=99322">bug 99322</a> from <a class="email" href="mailto:tim@buttersideup.com" title="Tim Small <tim@buttersideup.com>"> Tim Small</a> <pre>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.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are on the CC list for the bug.</li> <li>You are the QA Contact for the bug.</li> <li>You are the assignee for the bug.</li> </ul> </body> </html>