[PATCH 32/42] drm/i915: Introduce a global_seqno for each request

[Chris Wilson <chris@chris-wilson.co.uk>]

Though we will have multiple timelines, we still have a single timeline
of execution. This we can use to provide an execution and retirement order
of requests. This keeps tracking execution of requests simple, and vital
for preserving a single waiter (i.e. so that we can order the waiters so
that only the earliest to wakeup need be woken). To accomplish this we
distinguish the seqno used to order requests per-context (external) and
that used internally for execution.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c        |  2 +-
 drivers/gpu/drm/i915/i915_drv.h            |  4 ++--
 drivers/gpu/drm/i915/i915_gem.c            |  2 +-
 drivers/gpu/drm/i915/i915_gem_request.c    | 19 +++++++++++++-----
 drivers/gpu/drm/i915/i915_gem_request.h    | 32 +++++++++++++++++++++++++-----
 drivers/gpu/drm/i915/i915_gpu_error.c      |  2 +-
 drivers/gpu/drm/i915/i915_guc_submission.c |  4 ++--
 drivers/gpu/drm/i915/i915_trace.h          |  8 ++++----
 drivers/gpu/drm/i915/intel_breadcrumbs.c   |  8 +++++---
 drivers/gpu/drm/i915/intel_lrc.c           |  4 ++--
 drivers/gpu/drm/i915/intel_ringbuffer.c    | 14 ++++++-------
 11 files changed, 66 insertions(+), 33 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 4e452da96c39..77491eb3340f 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -644,7 +644,7 @@ static void print_request(struct seq_file *m,
 	rcu_read_lock();
 	task = pid ? pid_task(pid, PIDTYPE_PID) : NULL;
 	seq_printf(m, "%s%x [%x:%x] @ %d: %s [%d]\n", prefix,
-		   rq->fence.seqno, rq->ctx->hw_id, rq->fence.seqno,
+		   rq->global_seqno, rq->ctx->hw_id, rq->fence.seqno,
 		   jiffies_to_msecs(jiffies - rq->emitted_jiffies),
 		   task ? task->comm : "<unknown>",
 		   task ? task->pid : -1);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 582996ebebe5..78b54fb4b56b 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3991,7 +3991,7 @@ __i915_request_irq_complete(struct drm_i915_gem_request *req)
 	/* Before we do the heavier coherent read of the seqno,
 	 * check the value (hopefully) in the CPU cacheline.
 	 */
-	if (i915_gem_request_completed(req))
+	if (__i915_gem_request_completed(req))
 		return true;
 
 	/* Ensure our read of the seqno is coherent so that we
@@ -4042,7 +4042,7 @@ __i915_request_irq_complete(struct drm_i915_gem_request *req)
 			wake_up_process(tsk);
 		rcu_read_unlock();
 
-		if (i915_gem_request_completed(req))
+		if (__i915_gem_request_completed(req))
 			return true;
 	}
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 2887a318b9c0..f9a70971cb24 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2578,7 +2578,7 @@ static void i915_gem_reset_engine(struct intel_engine_cs *engine)
 		return;
 
 	DRM_DEBUG_DRIVER("resetting %s to restart from tail of request 0x%x\n",
-			 engine->name, request->fence.seqno);
+			 engine->name, request->global_seqno);
 
 	/* Setup the CS to resume from the breadcrumb of the hung request */
 	engine->reset_hw(engine, request);
diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 95748e0a27af..b29dddc35d34 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -375,7 +375,7 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
 	 * of being read by __i915_gem_active_get_rcu(). As such,
 	 * we have to be very careful when overwriting the contents. During
 	 * the RCU lookup, we change chase the request->engine pointer,
-	 * read the request->fence.seqno and increment the reference count.
+	 * read the request->global_seqno and increment the reference count.
 	 *
 	 * The reference count is incremented atomically. If it is zero,
 	 * the lookup knows the request is unallocated and complete. Otherwise,
@@ -417,6 +417,7 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
 	INIT_LIST_HEAD(&req->active_list);
 	req->i915 = dev_priv;
 	req->engine = engine;
+	req->global_seqno = seqno;
 	req->ctx = i915_gem_context_get(ctx);
 
 	/* No zalloc, must clear what we need by hand */
@@ -474,8 +475,15 @@ i915_gem_request_await_request(struct drm_i915_gem_request *to,
 		return ret < 0 ? ret : 0;
 	}
 
+	if (!from->global_seqno) {
+		ret = i915_sw_fence_await_dma_fence(&to->submit,
+						    &from->fence, 0,
+						    GFP_KERNEL);
+		return ret < 0 ? ret : 0;
+	}
+
 	idx = intel_engine_sync_index(from->engine, to->engine);
-	if (from->fence.seqno <= from->engine->semaphore.sync_seqno[idx])
+	if (from->global_seqno <= from->engine->semaphore.sync_seqno[idx])
 		return 0;
 
 	trace_i915_gem_ring_sync_to(to, from);
@@ -493,7 +501,7 @@ i915_gem_request_await_request(struct drm_i915_gem_request *to,
 			return ret;
 	}
 
-	from->engine->semaphore.sync_seqno[idx] = from->fence.seqno;
+	from->engine->semaphore.sync_seqno[idx] = from->global_seqno;
 	return 0;
 }
 
@@ -765,7 +773,7 @@ bool __i915_spin_request(const struct drm_i915_gem_request *req,
 
 	timeout_us += local_clock_us(&cpu);
 	do {
-		if (i915_gem_request_completed(req))
+		if (__i915_gem_request_completed(req))
 			return true;
 
 		if (signal_pending_state(state, current))
@@ -871,6 +879,7 @@ long i915_wait_request(struct drm_i915_gem_request *req,
 
 		GEM_BUG_ON(!i915_sw_fence_done(&req->submit));
 	}
+	GEM_BUG_ON(!req->global_seqno);
 
 	/* Optimistic short spin before touching IRQs */
 	if (i915_spin_request(req, state, 5))
@@ -880,7 +889,7 @@ long i915_wait_request(struct drm_i915_gem_request *req,
 	if (flags & I915_WAIT_LOCKED)
 		add_wait_queue(&req->i915->gpu_error.wait_queue, &reset);
 
-	intel_wait_init(&wait, req->fence.seqno);
+	intel_wait_init(&wait, req->global_seqno);
 	if (intel_engine_add_wait(req->engine, &wait))
 		/* In order to check that we haven't missed the interrupt
 		 * as we enabled it, we need to kick ourselves to do a
diff --git a/drivers/gpu/drm/i915/i915_gem_request.h b/drivers/gpu/drm/i915/i915_gem_request.h
index 378f523844bb..d1439f39420d 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.h
+++ b/drivers/gpu/drm/i915/i915_gem_request.h
@@ -87,6 +87,8 @@ struct drm_i915_gem_request {
 	struct i915_sw_fence submit;
 	wait_queue_t submitq;
 
+	u32 global_seqno;
+
 	/** GEM sequence number associated with the previous request,
 	 * when the HWS breadcrumb is equal to this the GPU is processing
 	 * this request.
@@ -163,7 +165,7 @@ void i915_gem_request_retire_upto(struct drm_i915_gem_request *req);
 static inline u32
 i915_gem_request_get_seqno(struct drm_i915_gem_request *req)
 {
-	return req ? req->fence.seqno : 0;
+	return req ? req->global_seqno : 0;
 }
 
 static inline struct intel_engine_cs *
@@ -248,17 +250,37 @@ static inline bool i915_seqno_passed(u32 seq1, u32 seq2)
 }
 
 static inline bool
-i915_gem_request_started(const struct drm_i915_gem_request *req)
+__i915_gem_request_started(const struct drm_i915_gem_request *req)
 {
+	GEM_BUG_ON(!req->global_seqno);
 	return i915_seqno_passed(intel_engine_get_seqno(req->engine),
 				 req->previous_seqno);
 }
 
 static inline bool
-i915_gem_request_completed(const struct drm_i915_gem_request *req)
+i915_gem_request_started(const struct drm_i915_gem_request *req)
 {
+	if (!req->global_seqno)
+		return false;
+
+	return __i915_gem_request_started(req);
+}
+
+static inline bool
+__i915_gem_request_completed(const struct drm_i915_gem_request *req)
+{
+	GEM_BUG_ON(!req->global_seqno);
 	return i915_seqno_passed(intel_engine_get_seqno(req->engine),
-				 req->fence.seqno);
+				 req->global_seqno);
+}
+
+static inline bool
+i915_gem_request_completed(const struct drm_i915_gem_request *req)
+{
+	if (!req->global_seqno)
+		return false;
+
+	return __i915_gem_request_completed(req);
 }
 
 bool __i915_spin_request(const struct drm_i915_gem_request *request,
@@ -266,7 +288,7 @@ bool __i915_spin_request(const struct drm_i915_gem_request *request,
 static inline bool i915_spin_request(const struct drm_i915_gem_request *request,
 				     int state, unsigned long timeout_us)
 {
-	return (i915_gem_request_started(request) &&
+	return (__i915_gem_request_started(request) &&
 		__i915_spin_request(request, state, timeout_us));
 }
 
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index d5d38c8361c2..b6bf6fafd849 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1202,7 +1202,7 @@ static void engine_record_requests(struct intel_engine_cs *engine,
 		}
 
 		erq = &ee->requests[count++];
-		erq->seqno = request->fence.seqno;
+		erq->seqno = request->global_seqno;
 		erq->jiffies = request->emitted_jiffies;
 		erq->head = request->head;
 		erq->tail = request->tail;
diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index 0a9a35d9401d..bc9ed266f4f1 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -521,7 +521,7 @@ static void guc_wq_item_append(struct i915_guc_client *gc,
 	wqi->context_desc = (u32)intel_lr_context_descriptor(rq->ctx, engine);
 
 	wqi->ring_tail = tail << WQ_RING_TAIL_SHIFT;
-	wqi->fence_id = rq->fence.seqno;
+	wqi->fence_id = rq->global_seqno;
 
 	kunmap_atomic(base);
 }
@@ -616,7 +616,7 @@ static void i915_guc_submit(struct drm_i915_gem_request *rq)
 		client->b_fail += 1;
 
 	guc->submissions[engine_id] += 1;
-	guc->last_seqno[engine_id] = rq->fence.seqno;
+	guc->last_seqno[engine_id] = rq->global_seqno;
 	spin_unlock(&client->wq_lock);
 }
 
diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
index 178798002a73..4c46f7c00323 100644
--- a/drivers/gpu/drm/i915/i915_trace.h
+++ b/drivers/gpu/drm/i915/i915_trace.h
@@ -466,7 +466,7 @@ TRACE_EVENT(i915_gem_ring_sync_to,
 			   __entry->dev = from->i915->drm.primary->index;
 			   __entry->sync_from = from->engine->id;
 			   __entry->sync_to = to->engine->id;
-			   __entry->seqno = from->fence.seqno;
+			   __entry->seqno = from->global_seqno;
 			   ),
 
 	    TP_printk("dev=%u, sync-from=%u, sync-to=%u, seqno=%u",
@@ -489,7 +489,7 @@ TRACE_EVENT(i915_gem_ring_dispatch,
 	    TP_fast_assign(
 			   __entry->dev = req->i915->drm.primary->index;
 			   __entry->ring = req->engine->id;
-			   __entry->seqno = req->fence.seqno;
+			   __entry->seqno = req->global_seqno;
 			   __entry->flags = flags;
 			   fence_enable_sw_signaling(&req->fence);
 			   ),
@@ -534,7 +534,7 @@ DECLARE_EVENT_CLASS(i915_gem_request,
 	    TP_fast_assign(
 			   __entry->dev = req->i915->drm.primary->index;
 			   __entry->ring = req->engine->id;
-			   __entry->seqno = req->fence.seqno;
+			   __entry->seqno = req->global_seqno;
 			   ),
 
 	    TP_printk("dev=%u, ring=%u, seqno=%u",
@@ -596,7 +596,7 @@ TRACE_EVENT(i915_gem_request_wait_begin,
 	    TP_fast_assign(
 			   __entry->dev = req->i915->drm.primary->index;
 			   __entry->ring = req->engine->id;
-			   __entry->seqno = req->fence.seqno;
+			   __entry->seqno = req->global_seqno;
 			   __entry->blocking =
 				     mutex_is_locked(&req->i915->drm.struct_mutex);
 			   ),
diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
index 495611b7068d..5fd82b17a706 100644
--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
@@ -504,9 +504,11 @@ void intel_engine_enable_signaling(struct drm_i915_gem_request *request)
 
 	/* locked by fence_enable_sw_signaling() */
 	assert_spin_locked(&request->lock);
+	if (!request->global_seqno)
+		return;
 
 	request->signaling.wait.tsk = b->signaler;
-	request->signaling.wait.seqno = request->fence.seqno;
+	request->signaling.wait.seqno = request->global_seqno;
 	i915_gem_request_get(request);
 
 	spin_lock(&b->lock);
@@ -530,8 +532,8 @@ void intel_engine_enable_signaling(struct drm_i915_gem_request *request)
 	p = &b->signals.rb_node;
 	while (*p) {
 		parent = *p;
-		if (i915_seqno_passed(request->fence.seqno,
-				      to_signaler(parent)->fence.seqno)) {
+		if (i915_seqno_passed(request->global_seqno,
+				      to_signaler(parent)->global_seqno)) {
 			p = &parent->rb_right;
 			first = false;
 		} else {
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 6acecfc41f5e..fb0e020fdfeb 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1584,7 +1584,7 @@ static int gen8_emit_request(struct drm_i915_gem_request *request)
 			intel_hws_seqno_address(request->engine) |
 			MI_FLUSH_DW_USE_GTT);
 	intel_ring_emit(ring, 0);
-	intel_ring_emit(ring, request->fence.seqno);
+	intel_ring_emit(ring, request->global_seqno);
 	intel_ring_emit(ring, MI_USER_INTERRUPT);
 	intel_ring_emit(ring, MI_NOOP);
 	return intel_logical_ring_advance(request);
@@ -1613,7 +1613,7 @@ static int gen8_emit_request_render(struct drm_i915_gem_request *request)
 			 PIPE_CONTROL_QW_WRITE));
 	intel_ring_emit(ring, intel_hws_seqno_address(request->engine));
 	intel_ring_emit(ring, 0);
-	intel_ring_emit(ring, i915_gem_request_get_seqno(request));
+	intel_ring_emit(ring, request->global_seqno);
 	/* We're thrashing one dword of HWS. */
 	intel_ring_emit(ring, 0);
 	intel_ring_emit(ring, MI_USER_INTERRUPT);
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index ec06d75a42aa..437eba266794 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1240,7 +1240,7 @@ static int gen8_rcs_signal(struct drm_i915_gem_request *req)
 				PIPE_CONTROL_CS_STALL);
 		intel_ring_emit(ring, lower_32_bits(gtt_offset));
 		intel_ring_emit(ring, upper_32_bits(gtt_offset));
-		intel_ring_emit(ring, req->fence.seqno);
+		intel_ring_emit(ring, req->global_seqno);
 		intel_ring_emit(ring, 0);
 		intel_ring_emit(ring,
 				MI_SEMAPHORE_SIGNAL |
@@ -1276,7 +1276,7 @@ static int gen8_xcs_signal(struct drm_i915_gem_request *req)
 				lower_32_bits(gtt_offset) |
 				MI_FLUSH_DW_USE_GTT);
 		intel_ring_emit(ring, upper_32_bits(gtt_offset));
-		intel_ring_emit(ring, req->fence.seqno);
+		intel_ring_emit(ring, req->global_seqno);
 		intel_ring_emit(ring,
 				MI_SEMAPHORE_SIGNAL |
 				MI_SEMAPHORE_TARGET(waiter->hw_id));
@@ -1309,7 +1309,7 @@ static int gen6_signal(struct drm_i915_gem_request *req)
 		if (i915_mmio_reg_valid(mbox_reg)) {
 			intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
 			intel_ring_emit_reg(ring, mbox_reg);
-			intel_ring_emit(ring, req->fence.seqno);
+			intel_ring_emit(ring, req->global_seqno);
 		}
 	}
 
@@ -1340,7 +1340,7 @@ static int i9xx_emit_request(struct drm_i915_gem_request *req)
 
 	intel_ring_emit(ring, MI_STORE_DWORD_INDEX);
 	intel_ring_emit(ring, I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
-	intel_ring_emit(ring, req->fence.seqno);
+	intel_ring_emit(ring, req->global_seqno);
 	intel_ring_emit(ring, MI_USER_INTERRUPT);
 	intel_ring_advance(ring);
 
@@ -1390,7 +1390,7 @@ static int gen8_render_emit_request(struct drm_i915_gem_request *req)
 			       PIPE_CONTROL_QW_WRITE));
 	intel_ring_emit(ring, intel_hws_seqno_address(engine));
 	intel_ring_emit(ring, 0);
-	intel_ring_emit(ring, i915_gem_request_get_seqno(req));
+	intel_ring_emit(ring, req->global_seqno);
 	/* We're thrashing one dword of HWS. */
 	intel_ring_emit(ring, 0);
 	intel_ring_emit(ring, MI_USER_INTERRUPT);
@@ -1428,7 +1428,7 @@ gen8_ring_sync_to(struct drm_i915_gem_request *req,
 			MI_SEMAPHORE_WAIT |
 			MI_SEMAPHORE_GLOBAL_GTT |
 			MI_SEMAPHORE_SAD_GTE_SDD);
-	intel_ring_emit(ring, signal->fence.seqno);
+	intel_ring_emit(ring, signal->global_seqno);
 	intel_ring_emit(ring, lower_32_bits(offset));
 	intel_ring_emit(ring, upper_32_bits(offset));
 	intel_ring_advance(ring);
@@ -1466,7 +1466,7 @@ gen6_ring_sync_to(struct drm_i915_gem_request *req,
 	 * seqno is >= the last seqno executed. However for hardware the
 	 * comparison is strictly greater than.
 	 */
-	intel_ring_emit(ring, signal->fence.seqno - 1);
+	intel_ring_emit(ring, signal->global_seqno - 1);
 	intel_ring_emit(ring, 0);
 	intel_ring_emit(ring, MI_NOOP);
 	intel_ring_advance(ring);
-- 
2.9.3

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