<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_REOPENED " title="REOPENED - [CI][BAT bsw] igt@gem_* - fail - Failed assertion: !"GPU hung"" href="https://bugs.freedesktop.org/show_bug.cgi?id=108656#c16">Comment # 16</a> on <a class="bz_bug_link bz_status_REOPENED " title="REOPENED - [CI][BAT bsw] igt@gem_* - fail - Failed assertion: !"GPU hung"" href="https://bugs.freedesktop.org/show_bug.cgi?id=108656">bug 108656</a> from <a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> Chris Wilson</a> <pre>Step 1: commit 490b8c65b9db45896769e1095e78725775f47b3e (HEAD -> drm-intel-next-queued, drm-intel/for-linux-next, drm-intel/drm-intel-next-queued) Author: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>> Date: Thu Dec 6 08:44:31 2018 +0000 drm/i915/execlists: Apply a full mb before execution for Braswell Braswell is really picky about having our writes posted to memory before we execute or else the GPU may see stale values. A wmb() is insufficient as it only ensures the writes are visible to other cores, we need a full mb() to ensure the writes are in memory and visible to the GPU. The most frequent failure in flushing before execution is that we see stale PTE values and execute the wrong pages. References: 987abd5c62f9 ("drm/i915/execlists: Force write serialisation into context image vs execution") Signed-off-by: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>> Cc: Mika Kuoppala <<a href="mailto:mika.kuoppala@linux.intel.com">mika.kuoppala@linux.intel.com</a>> Cc: Tvrtko Ursulin <<a href="mailto:tvrtko.ursulin@intel.com">tvrtko.ursulin@intel.com</a>> Cc: Joonas Lahtinen <<a href="mailto:joonas.lahtinen@linux.intel.com">joonas.lahtinen@linux.intel.com</a>> Cc: <a href="mailto:stable@vger.kernel.org">stable@vger.kernel.org</a> Reviewed-by: Tvrtko Ursulin <<a href="mailto:tvrtko.ursulin@intel.com">tvrtko.ursulin@intel.com</a>></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> </ul> </body> </html>