drm/i915/gem: Peek at the inflight context

If supported by the backend, we can quickly look at the context's
inflight engine rather than search along the active list to confirm.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201229144114.31686-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gem/i915_gem_context.c

@@ -423,6 +423,9 @@ static struct intel_engine_cs *active_engine(struct intel_context *ce)
 	struct intel_engine_cs *engine = NULL;
 	struct i915_request *rq;
 
+	if (intel_context_has_inflight(ce))
+		return intel_context_inflight(ce);
+
 	if (!ce->timeline)
 		return NULL;
 

drivers/gpu/drm/i915/gt/intel_context.h

@@ -191,6 +191,11 @@ static inline bool intel_context_is_closed(const struct intel_context *ce)
 	return test_bit(CONTEXT_CLOSED_BIT, &ce->flags);
 }
 
+static inline bool intel_context_has_inflight(const struct intel_context *ce)
+{
+	return test_bit(COPS_HAS_INFLIGHT_BIT, &ce->ops->flags);
+}
+
 static inline bool intel_context_use_semaphores(const struct intel_context *ce)
 {
 	return test_bit(CONTEXT_USE_SEMAPHORES, &ce->flags);

drivers/gpu/drm/i915/gt/intel_context_types.h

@@ -30,6 +30,10 @@ struct intel_context;
 struct intel_ring;
 
 struct intel_context_ops {
+	unsigned long flags;
+#define COPS_HAS_INFLIGHT_BIT 0
+#define COPS_HAS_INFLIGHT BIT(COPS_HAS_INFLIGHT_BIT)
+
 	int (*alloc)(struct intel_context *ce);
 
 	int (*pre_pin)(struct intel_context *ce, struct i915_gem_ww_ctx *ww, void **vaddr);

drivers/gpu/drm/i915/gt/intel_execlists_submission.c

@@ -2531,6 +2531,8 @@ static int execlists_context_alloc(struct intel_context *ce)
 }
 
 static const struct intel_context_ops execlists_context_ops = {
+	.flags = COPS_HAS_INFLIGHT,
+
 	.alloc = execlists_context_alloc,
 
 	.pre_pin = execlists_context_pre_pin,
@@ -3441,6 +3443,8 @@ static void virtual_context_exit(struct intel_context *ce)
 }
 
 static const struct intel_context_ops virtual_context_ops = {
+	.flags = COPS_HAS_INFLIGHT,
+
 	.alloc = virtual_context_alloc,
 
 	.pre_pin = virtual_context_pre_pin,