Quoting Mika Kuoppala (2018-04-25 12:19:08) > Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> 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) Just keep running gem_ctx_switch. Switching between the static set of contexts, no rebind pressure whatsoever. > > 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 <chris@xxxxxxxxxxxxxxxxxx> > > --- > > 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? Sure can try, but the error state doesn't indicate TAIL==HEAD as would be the issue with WaIdleLiteRestore (restoring to an idle ring wouldn't generate the arbitration event, so no more context switches). -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
