From e19dcde0b6680f7f8d449b6aac4302220960d8ab Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed, 25 Mar 2020 10:13:58 +0000
Subject: drm/i915/execlists: Drop setting sibling priority hint on virtual
Git-commit: 9bf7c31386e511cc9671a252886dcb080bf08579
Patch-mainline: v5.8-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
 engines

We set the priority hint on execlists to avoid executing the tasklet for
when we know that there will be no change in execution order. However,
as we set it from the virtual engine for all siblings, but only one
physical engine may respond, we leave the hint set on the others
stopping direct submission that could take place.

If we do not set the hint, we may attempt direct submission even if we
don't expect to submit. If we set the hint, we may not do any submission
until the tasklet is run (and sometimes we may park the engine before
that has had a chance). Ergo there's only a minor ill-effect on mixed
virtual/physical engine workloads where we may try and fail to do direct
submission more often than required. (Pure virtual / engine workloads
will have redundant tasklet execution suppressed as normal.)

Closes: https://gitlab.freedesktop.org/drm/intel/issues/1522
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200325101358.12231-1-chris@chris-wilson.co.uk
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/gt/intel_lrc.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index d8d0b826cc55..35b13dda7fc7 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -5037,10 +5037,8 @@ static void virtual_submission_tasklet(unsigned long data)
 submit_engine:
 		GEM_BUG_ON(RB_EMPTY_NODE(&node->rb));
 		node->prio = prio;
-		if (first && prio > sibling->execlists.queue_priority_hint) {
-			sibling->execlists.queue_priority_hint = prio;
+		if (first && prio > sibling->execlists.queue_priority_hint)
 			tasklet_hi_schedule(&sibling->execlists.tasklet);
-		}
 
 		spin_unlock(&sibling->active.lock);
 	}
-- 
2.28.0