Sometimes we want to emit a terminator request, a request that flushes
the pipeline and allows no request to come after it. This can be used
for a "preempt-to-idle" to ensure that upon processing the
context-switch to that request, all other active contexts have been
flushed.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_lrc.c | 6 ++++++
drivers/gpu/drm/i915/i915_request.h | 10 ++++++++--
2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 6b3b9026d840..5a6f1b1ddefa 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -804,6 +804,9 @@ static bool can_merge_rq(const struct i915_request *prev,
GEM_BUG_ON(prev == next);
GEM_BUG_ON(!assert_priority_queue(prev, next));
+ if (i915_request_has_sentinel(prev))
+ return false;
+
if (!can_merge_ctx(prev->hw_context, next->hw_context))
return false;
@@ -1307,6 +1310,9 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
if (last->hw_context == rq->hw_context)
goto done;
+ if (i915_request_has_sentinel(last))
+ goto done;
+
/*
* If GVT overrides us we only ever submit
* port[0], leaving port[1] empty. Note that we
diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
index 2a5d682aa6b1..49c21672da3d 100644
--- a/drivers/gpu/drm/i915/i915_request.h
+++ b/drivers/gpu/drm/i915/i915_request.h
@@ -216,8 +216,9 @@ struct i915_request {
unsigned long emitted_jiffies;
unsigned long flags;
-#define I915_REQUEST_WAITBOOST BIT(0)
-#define I915_REQUEST_NOPREEMPT BIT(1)
+#define I915_REQUEST_WAITBOOST BIT(0)
+#define I915_REQUEST_NOPREEMPT BIT(1)
+#define I915_REQUEST_SENTINEL BIT(2)
/** timeline->request entry for this request */
struct list_head link;
@@ -439,6 +440,11 @@ static inline bool i915_request_has_nopreempt(const struct i915_request *rq)
return unlikely(rq->flags & I915_REQUEST_NOPREEMPT);
}
+static inline bool i915_request_has_sentinel(const struct i915_request *rq)
+{
+ return unlikely(rq->flags & I915_REQUEST_SENTINEL);
+}
+
long i915_retire_requests(struct drm_i915_private *i915, long timeout);
#endif /* I915_REQUEST_H */
--
2.23.0
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