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

diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c
index 992b00f..0b12d50 100644 (file)
--- 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;

diff --git a/drivers/gpu/drm/i915/selftests/i915_active.c b/drivers/gpu/drm/i915/selftests/i915_active.c
index ef572a0..067e30b 100644 (file)
--- a/drivers/gpu/drm/i915/selftests/i915_active.c
+++ b/drivers/gpu/drm/i915/selftests/i915_active.c
@@ -201,11 +201,57 @@ static int live_active_retire(void *arg)
        return err;
 }
 
+static int live_active_barrier(void *arg)
+{
+       struct drm_i915_private *i915 = arg;
+       struct intel_engine_cs *engine;
+       struct live_active *active;
+       int err = 0;
+
+       /* Check that we get a callback when requests retire upon waiting */
+
+       active = __live_alloc(i915);
+       if (!active)
+               return -ENOMEM;
+
+       err = i915_active_acquire(&active->base);
+       if (err)
+               goto out;
+
+       for_each_uabi_engine(engine, i915) {
+               err = i915_active_acquire_preallocate_barrier(&active->base,
+                                                             engine);
+               if (err)
+                       break;
+
+               i915_active_acquire_barrier(&active->base);
+       }
+
+       i915_active_release(&active->base);
+
+       if (err == 0)
+               err = i915_active_wait(&active->base);
+
+       if (err == 0 && !READ_ONCE(active->retired)) {
+               pr_err("i915_active not retired after flushing barriers!\n");
+               err = -EINVAL;
+       }
+
+out:
+       __live_put(active);
+
+       if (igt_flush_test(i915))
+               err = -EIO;
+
+       return err;
+}
+
 int i915_active_live_selftests(struct drm_i915_private *i915)
 {
        static const struct i915_subtest tests[] = {
                SUBTEST(live_active_wait),
                SUBTEST(live_active_retire),
+               SUBTEST(live_active_barrier),
        };
 
        if (intel_gt_is_wedged(&i915->gt))