drm/i915: Flush idle barriers when waiting

If we do find ourselves with an idle barrier inside our active while
waiting, attempt to flush it by emitting a pulse using the kernel
context.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Steve Carbonari <steven.carbonari@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200225192206.1107336-1-chris@chris-wilson.co.uk

1 files changed, 33 insertions, 9 deletions

diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c
index 992b00fc5745..0b12d5023800 100644
--- a/drivers/gpu/drm/i915/i915_active.c
+++ b/drivers/gpu/drm/i915/i915_active.c
@@ -7,6 +7,7 @@
 #include <linux/debugobjects.h>
 
 #include "gt/intel_context.h"
+#include "gt/intel_engine_heartbeat.h"
 #include "gt/intel_engine_pm.h"
 #include "gt/intel_ring.h"
 
@@ -460,26 +461,49 @@ static void enable_signaling(struct i915_active_fence *active)
 	dma_fence_put(fence);
 }
 
-int i915_active_wait(struct i915_active *ref)
+static int flush_barrier(struct active_node *it)
 {
-	struct active_node *it, *n;
-	int err = 0;
+	struct intel_engine_cs *engine;
 
-	might_sleep();
+	if (likely(!is_barrier(&it->base)))
+		return 0;
 
-	if (!i915_active_acquire_if_busy(ref))
+	engine = __barrier_to_engine(it);
+	smp_rmb(); /* serialise with add_active_barriers */
+	if (!is_barrier(&it->base))
 		return 0;
 
-	/* Flush lazy signals */
+	return intel_engine_flush_barriers(engine);
+}
+
+static int flush_lazy_signals(struct i915_active *ref)
+{
+	struct active_node *it, *n;
+	int err = 0;
+
 	enable_signaling(&ref->excl);
 	rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
-		if (is_barrier(&it->base)) /* unconnected idle barrier */
-			continue;
+		err = flush_barrier(it); /* unconnected idle barrier? */
+		if (err)
+			break;
 
 		enable_signaling(&it->base);
 	}
-	/* Any fence added after the wait begins will not be auto-signaled */
 
+	return err;
+}
+
+int i915_active_wait(struct i915_active *ref)
+{
+	int err;
+
+	might_sleep();
+
+	if (!i915_active_acquire_if_busy(ref))
+		return 0;
+
+	/* Any fence added after the wait begins will not be auto-signaled */
+	err = flush_lazy_signals(ref);
 	i915_active_release(ref);
 	if (err)
 		return err;