<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - [GLK DSI] Black screen after grub - Ubuntu 18.04 - kernel latest tip 21.11.2018" href="https://bugs.freedesktop.org/show_bug.cgi?id=108826#c13">Comment # 13</a> on <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - [GLK DSI] Black screen after grub - Ubuntu 18.04 - kernel latest tip 21.11.2018" href="https://bugs.freedesktop.org/show_bug.cgi?id=108826">bug 108826</a> from <a class="email" href="mailto:jani.nikula@intel.com" title="Jani Nikula <jani.nikula@intel.com>"> Jani Nikula</a> <pre>One idea for debugging this: 1) boot *without* loading i915 2) get register dump using intel_reg (from the igt-gpu-tools [1]) 3) modprobe i915 (presumably screen goes black at this point) 4) repeat the register dump Alas I think intel_reg dump still falls short for MIPI DSI register dumps. Someone from our side should provide a register spec file to use with intel_reg to include all the relevant registers. (One of the reasons we're not dumping the DSI registers by default is that reading them hangs the machine if DSI isn't properly powered and clocks enabled.) [1] <a href="https://cgit.freedesktop.org/drm/igt-gpu-tools/">https://cgit.freedesktop.org/drm/igt-gpu-tools/</a></pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> <li>You are on the CC list for the bug.</li> <li>You are the QA Contact for the bug.</li> </ul> </body> </html>