<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#c22">Comment # 22</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>Hi Paul (reply to #21), Totally agree on you. The title of this issue is really confusing. Customer reported it suffered from system hung when plug-in into VGA port originally in SKL-U platform, and didn't say how design of display in DUT. After checking its internal display design of DUT, it uses one DP MST-enabled Hub (Synaptics DP Hub VMM3320) and one DP-to-VGA converter to extend theirs display port for 2 DPs and 2 VGAs. For <a href="show_bug.cgi?id=91791#c1">comment #1</a>, I used DP-to-VGA converters (DP 1.1a & DP 1.2) to check it, they works well in my Intel SKL-U CRB. For <a href="show_bug.cgi?id=91791#c7">comment #7</a>, I used DP 1.2 MST-enabled HUB (Sunix IT DisplayPort to Dual Graphics Splitter 1-input DP and 2 output DPs) to test this issue in SKL-U Intel CRB, i.e. using CRB's miniDP port connecting to DP MST Hub for DP MST on two DP monitors via that DP MST Hub. It suffered from the same issue in my Intel SKL-U CRB (dp training error from intel_mst_pre_enable_dp()/intel_dp_mst_compute_config()). For <a href="show_bug.cgi?id=91791#c13">comment #13</a> and #14, it seems to cause trouble between source MST link computation among DP source/branch/sink when enabling MST display (but aux works well). Then disable MST for SST between source and sink makes test (from #7 with one DP 1.2 monitor & one DP 1.1a monitor) working well with functionality of DP MST in Ubuntu 15.04 (but still not try DP daisy chain and guess could be trouble due to lacking MST). All of them were tested based on drm-intel-nightly-2015/10/19. Thanks! Gary</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> <li>You are on the CC list for the bug.</li> <li>You are the assignee for the bug.</li> </ul> </body> </html>