<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - [KBL][drm:fw_domains_get [i915]] *ERROR* blitter: timed out waiting for forcewake ack request." href="https://bugs.freedesktop.org/show_bug.cgi?id=102051#c5">Comment # 5</a> on <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - [KBL][drm:fw_domains_get [i915]] *ERROR* blitter: timed out waiting for forcewake ack request." href="https://bugs.freedesktop.org/show_bug.cgi?id=102051">bug 102051</a> from <a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> Chris Wilson</a> <pre>Mika suspected that commit 7130630323c562597191653560963e61c5bd0f57 Author: Mika Kuoppala <<a href="mailto:mika.kuoppala@linux.intel.com">mika.kuoppala@linux.intel.com</a>> Date: Thu Nov 2 11:48:36 2017 +0200 drm/i915: Use fallback forcewake if primary ack missing There is a possibility on gen9 hardware to miss the forcewake ack message. The recommended workaround is to use another free bit and toggle it until original bit is successfully acknowledged. Some future gen9 revs might or might not fix the underlying issue but using fallback forcewake bit dance can be considered as harmless: without the ack timeout we never reach the fallback bit forcewake. Thus as of now we adopt a blanket approach for all gen9 and leave the bypassing the fallback bit approach for future patches if corresponding hw revisions do appear. Commit 83e3337204b2 ("drm/i915: Increase maximum polling time to 50ms for forcewake request/clear ack") did increase the forcewake timeout. If the issue was a delayed ack, future work could include finding a suitable timeout value both for primary ack and reserve toggle to reduce the worst case latency. v2: use bit 15, naming, comment (Chris), only wait fallback ack v3: fix return on fallback, backoff after fallback write (Chris) v4: udelay on first pass, grammar (Chris) v4: s/reserve/fallback References: HSDES #1604254524 References: <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - [KBL][drm:fw_domains_get [i915]] *ERROR* blitter: timed out waiting for forcewake ack request." href="show_bug.cgi?id=102051">https://bugs.freedesktop.org/show_bug.cgi?id=102051</a> Cc: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>> Cc: Rodrigo Vivi <<a href="mailto:rodrigo.vivi@intel.com">rodrigo.vivi@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: Sagar Arun Kamble <<a href="mailto:sagar.a.kamble@intel.com">sagar.a.kamble@intel.com</a>> Signed-off-by: Mika Kuoppala <<a href="mailto:mika.kuoppala@linux.intel.com">mika.kuoppala@linux.intel.com</a>> Reviewed-by: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>> Link: <a href="https://patchwork.freedesktop.org/patch/msgid/20171102094836.2506-1-mika.kuoppala@linux.intel.com">https://patchwork.freedesktop.org/patch/msgid/20171102094836.2506-1-mika.kuoppala@linux.intel.com</a> may help, but live_uncore is deliberately unfriendly to the hw...</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>