<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - [SKL-U] System hang when plug in a VGA monitor" href="https://bugs.freedesktop.org/show_bug.cgi?id=91791#c24">Comment # 24</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - [SKL-U] System hang when plug in a VGA monitor" href="https://bugs.freedesktop.org/show_bug.cgi?id=91791">bug 91791</a> from <a class="email" href="mailto:gary.c.wang@intel.com" title="Gary Wang <gary.c.wang@intel.com>"> Gary Wang</a> <pre>Created <a href="attachment.cgi?id=119332" name="attach_119332" title="Picture: suffers issue when plug-in DP MST-enabled with modeset=1">attachment 119332</a> <a href="attachment.cgi?id=119332&action=edit" title="Picture: suffers issue when plug-in DP MST-enabled with modeset=1">[details]</a> Picture: suffers issue when plug-in DP MST-enabled with modeset=1 Hi Paul, I used following information to this issue for QA's reference, Intel CRB: Skylake Client platform/Skylake U DDR3L RVP7 CPU: i3-6100U CPU @ 2.30GHz (family: 0x6, model: 0x4e, stepping: 0x3) BIOS version: BIOS SKLSE2R1.R00.X097.B02.1509020030 09/02/2015 Display: CRB's miniDP with DP MST-enabled Hub (Sunix IT DisplayPort, <a href="http://www.amazon.com/IT-DisplayPort-Graphics-Splitter-DPD2001/dp/B00JATFVXI">http://www.amazon.com/IT-DisplayPort-Graphics-Splitter-DPD2001/dp/B00JATFVXI</a>) Linux Gfx kernel Driver: drm-intel-nightly-2015/10/19 Reproduce steps: 1. Boot into Ubuntu 15.04 with kernel drm-intel-nightly-2015/10/19 successfully without plug-in mini-DP port 2. Prepare DP MST environment by miniDP cable-->DP MST-enabled HUB-->Connect to both/either DP 1.2 MST-supported monitor and/or DP 1.1a monitor 3. Plug-in miniDP cable into CRB's miniPort (it will encounter it immediately) Warning: f booting with DP MST environment (i.e. step2/3), it suffered system hung immediately (please refer the picture). BTW, from my analysis for booting by kernel drm-intel-nightly-2015/10/19 + x11 only, it seems to no problem on DP MST connecting (sometime MSTM_CTRL failed to write) but failed in its enabling. ... Feb 17 22:22:38 test kernel: [ 546.442146] [drm:intel_dp_check_mst_status] channel EQ not ok, retraining Feb 17 22:22:38 test kernel: [ 546.443339] [drm:intel_dp_set_signal_levels] Using signal levels 00000000 Feb 17 22:22:38 test kernel: [ 546.443340] [drm:intel_dp_set_signal_levels] Using vswing level 0 Feb 17 22:22:38 test kernel: [ 546.443341] [drm:intel_dp_set_signal_levels] Using pre-emphasis level 0 ... Feb 17 22:22:38 test kernel: [ 547.039900] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up ... Thanks for your help! Gary</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are on the CC list for the bug.</li> </ul> </body> </html>