Chris Wilson <ch...@chris-wilson.co.uk> writes: > When WaIdleLiteRestore isn't enough. > > Fixes an odd hang on gen8 (both bsw and bdw) during gem_ctx_switch,
Do you have a testcase name? (testcase tag would be nice too) > where by all intents and purposes if we trigger a lite-restore as it is > processing the pipecontrol flushes, the RING is restored to the oword s/RING/RING_HEAD ? > following the command and tries to execute the destination address for > the pipecontrol rather than a valid command. With the theory being that > it doesn't like RING_HEAD being within a cacheline of the restored > RING_TAIL, we can evade that issue by not triggering a lite-restore if > we know we are inside the last request. > > Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk> > --- > drivers/gpu/drm/i915/intel_lrc.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/gpu/drm/i915/intel_lrc.c > b/drivers/gpu/drm/i915/intel_lrc.c > index 029901a8fa38..5c50263e45d3 100644 > --- a/drivers/gpu/drm/i915/intel_lrc.c > +++ b/drivers/gpu/drm/i915/intel_lrc.c > @@ -639,6 +639,19 @@ static void execlists_dequeue(struct intel_engine_cs > *engine) > if (port_count(&port[1])) > goto unlock; > > + /* > + * Skip invoking a lite-restore if we know we have already > + * started processing the last request queued to HW. This > + * prevents a mystery *unrecoverable* hang on gen8, maybe > + * related to updating TAIL within a cacheline of HEAD? (As Did you try with WA_TAIL_DWORDS 16? -Mika > + * there is still a delay between submitting the ESLP update > + * and HW responding, we may still encounter whatever condition > + * trips up, just less often.) > + */ > + if (i915_seqno_passed(intel_engine_get_seqno(engine), > + last->global_seqno - 1)) > + goto unlock; > + > /* > * WaIdleLiteRestore:bdw,skl > * Apply the wa NOOPs to prevent > -- > 2.17.0 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
