From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 6 Mar 2018 13:01:43 +0000
Subject: drm/i915: Flush waiters on seqno wraparound
Git-commit: f41d19beccfebb84abc729e2d8ece0c368b2152f
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Previously, we would spin waiting for all waiters to wake up and notice
their request had completed before we would reset the seqno upon
wraparound.  However, we can mark their waits as complete and wake them
up directly using the existing machinery for handling the flushing of
missed wakeups when idling.

Suggested-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180306130143.13312-2-chris@chris-wilson.co.uk

Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/i915/i915_request.c      |    6 ++----
 drivers/gpu/drm/i915/intel_breadcrumbs.c |   19 -------------------
 drivers/gpu/drm/i915/intel_ringbuffer.h  |    1 -
 3 files changed, 2 insertions(+), 24 deletions(-)

--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -217,10 +217,8 @@ static int reset_all_global_seqno(struct
 		struct intel_timeline *tl = engine->timeline;
 
 		if (!i915_seqno_passed(seqno, tl->seqno)) {
-			/* spin until threads are complete */
-			while (intel_breadcrumbs_busy(engine))
-				cond_resched();
-
+			/* Flush any waiters before we reuse the seqno */
+			intel_engine_disarm_breadcrumbs(engine);
 			GEM_BUG_ON(!list_empty(&engine->breadcrumbs.signals));
 		}
 
--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
@@ -873,25 +873,6 @@ void intel_engine_fini_breadcrumbs(struc
 	cancel_fake_irq(engine);
 }
 
-bool intel_breadcrumbs_busy(struct intel_engine_cs *engine)
-{
-	struct intel_breadcrumbs *b = &engine->breadcrumbs;
-	bool busy = false;
-
-	if (b->irq_wait) {
-		spin_lock_irq(&b->irq_lock);
-
-		if (b->irq_wait) {
-			wake_up_process(b->irq_wait->tsk);
-			busy = true;
-		}
-
-		spin_unlock_irq(&b->irq_lock);
-	}
-
-	return busy;
-}
-
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 #include "selftests/intel_breadcrumbs.c"
 #endif
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -950,7 +950,6 @@ void intel_engine_disarm_breadcrumbs(str
 
 void intel_engine_reset_breadcrumbs(struct intel_engine_cs *engine);
 void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine);
-bool intel_breadcrumbs_busy(struct intel_engine_cs *engine);
 
 static inline u32 *gen8_emit_pipe_control(u32 *batch, u32 flags, u32 offset)
 {