drm/i915: Flush waiters on seqno wraparound

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

1 files changed, 2 insertions, 4 deletions

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index d34a3e5800b7..d437beac3969 100644
--- 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 drm_i915_private *i915, u32 seqno)
 		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));
 		}