<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - [hsw DP-to-DVI] DP hot plug fails if booted without Monitor Attached" href="https://bugs.freedesktop.org/show_bug.cgi?id=85924#c4">Comment # 4</a> on <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - [hsw DP-to-DVI] DP hot plug fails if booted without Monitor Attached" href="https://bugs.freedesktop.org/show_bug.cgi?id=85924">bug 85924</a> from <a class="email" href="mailto:zoran.stojsavljevic@intel.com" title="Zoran Stojsavljevic <zoran.stojsavljevic@intel.com>"> Zoran Stojsavljevic</a> <pre>Hello Jani, Let me summarize some ideas and my thoughts here. It seems that on headless booting vBIOS, using mode 50h (assuming this mode is set), waits for some synch signals it sent to monitor if HW I/F (DP, eDP, HDMI, DVI, VGA) present. The timer is set. Once timer expires, vBIOS concludes that monitor is NOT present, then it disables host/monitor synch protocol and continues booting. If vBIOS does not detect any HW I/F, it automatically disables host/monitor synch protocol, then continues booting. So, while booting kernel, GFX driver in its init function should retest HW presense, and regardless enable host/monitor synch protocol again, or to make sure that monitor hot plug works, not to take blindly any vBIOS assumptions. My best guess. Thank you, Zoran</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>