drm/i915: Remove access to global seqno in the HWSP

Stop accessing the HWSP to read the global seqno, and stop tracking the
mirror in the engine's execution timeline -- it is unused.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190226094922.31617-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gpu_error.c

@@ -526,8 +526,6 @@ static void error_print_engine(struct drm_i915_error_state_buf *m,
 				   ee->vm_info.pp_dir_base);
 		}
 	}
-	err_printf(m, "  seqno: 0x%08x\n", ee->seqno);
-	err_printf(m, "  last_seqno: 0x%08x\n", ee->last_seqno);
 	err_printf(m, "  ring->head: 0x%08x\n", ee->cpu_ring_head);
 	err_printf(m, "  ring->tail: 0x%08x\n", ee->cpu_ring_tail);
 	err_printf(m, "  hangcheck timestamp: %dms (%lu%s)\n",
@@ -1216,8 +1214,6 @@ static void error_record_engine_registers(struct i915_gpu_state *error,
 
 	ee->instpm = I915_READ(RING_INSTPM(engine->mmio_base));
 	ee->acthd = intel_engine_get_active_head(engine);
-	ee->seqno = intel_engine_get_seqno(engine);
-	ee->last_seqno = intel_engine_last_submit(engine);
 	ee->start = I915_READ_START(engine);
 	ee->head = I915_READ_HEAD(engine);
 	ee->tail = I915_READ_TAIL(engine);

drivers/gpu/drm/i915/i915_gpu_error.h

@@ -94,8 +94,6 @@ struct i915_gpu_state {
 		u32 cpu_ring_head;
 		u32 cpu_ring_tail;
 
-		u32 last_seqno;
-
 		/* Register state */
 		u32 start;
 		u32 tail;
@@ -108,7 +106,6 @@ struct i915_gpu_state {
 		u32 bbstate;
 		u32 instpm;
 		u32 instps;
-		u32 seqno;
 		u64 bbaddr;
 		u64 acthd;
 		u32 fault_reg;

drivers/gpu/drm/i915/i915_request.c

@@ -179,12 +179,11 @@ static void free_capture_list(struct i915_request *request)
 static void __retire_engine_request(struct intel_engine_cs *engine,
 				    struct i915_request *rq)
 {
-	GEM_TRACE("%s(%s) fence %llx:%lld, global=%d, current %d:%d\n",
+	GEM_TRACE("%s(%s) fence %llx:%lld, global=%d, current %d\n",
 		  __func__, engine->name,
 		  rq->fence.context, rq->fence.seqno,
 		  rq->global_seqno,
-		  hwsp_seqno(rq),
-		  intel_engine_get_seqno(engine));
+		  hwsp_seqno(rq));
 
 	GEM_BUG_ON(!i915_request_completed(rq));
 
@@ -243,12 +242,11 @@ static void i915_request_retire(struct i915_request *request)
 {
 	struct i915_active_request *active, *next;
 
-	GEM_TRACE("%s fence %llx:%lld, global=%d, current %d:%d\n",
+	GEM_TRACE("%s fence %llx:%lld, global=%d, current %d\n",
 		  request->engine->name,
 		  request->fence.context, request->fence.seqno,
 		  request->global_seqno,
-		  hwsp_seqno(request),
-		  intel_engine_get_seqno(request->engine));
+		  hwsp_seqno(request));
 
 	lockdep_assert_held(&request->i915->drm.struct_mutex);
 	GEM_BUG_ON(!i915_sw_fence_signaled(&request->submit));
@@ -305,12 +303,11 @@ void i915_request_retire_upto(struct i915_request *rq)
 	struct intel_ring *ring = rq->ring;
 	struct i915_request *tmp;
 
-	GEM_TRACE("%s fence %llx:%lld, global=%d, current %d:%d\n",
+	GEM_TRACE("%s fence %llx:%lld, global=%d, current %d\n",
 		  rq->engine->name,
 		  rq->fence.context, rq->fence.seqno,
 		  rq->global_seqno,
-		  hwsp_seqno(rq),
-		  intel_engine_get_seqno(rq->engine));
+		  hwsp_seqno(rq));
 
 	lockdep_assert_held(&rq->i915->drm.struct_mutex);
 	GEM_BUG_ON(!i915_request_completed(rq));
@@ -354,12 +351,11 @@ void __i915_request_submit(struct i915_request *request)
 	struct intel_engine_cs *engine = request->engine;
 	u32 seqno;
 
-	GEM_TRACE("%s fence %llx:%lld -> global=%d, current %d:%d\n",
+	GEM_TRACE("%s fence %llx:%lld -> global=%d, current %d\n",
 		  engine->name,
 		  request->fence.context, request->fence.seqno,
 		  engine->timeline.seqno + 1,
-		  hwsp_seqno(request),
-		  intel_engine_get_seqno(engine));
+		  hwsp_seqno(request));
 
 	GEM_BUG_ON(!irqs_disabled());
 	lockdep_assert_held(&engine->timeline.lock);
@@ -371,7 +367,6 @@ void __i915_request_submit(struct i915_request *request)
 
 	seqno = next_global_seqno(&engine->timeline);
 	GEM_BUG_ON(!seqno);
-	GEM_BUG_ON(intel_engine_signaled(engine, seqno));
 
 	/* We may be recursing from the signal callback of another i915 fence */
 	spin_lock_nested(&request->lock, SINGLE_DEPTH_NESTING);
@@ -409,12 +404,11 @@ void __i915_request_unsubmit(struct i915_request *request)
 {
 	struct intel_engine_cs *engine = request->engine;
 
-	GEM_TRACE("%s fence %llx:%lld <- global=%d, current %d:%d\n",
+	GEM_TRACE("%s fence %llx:%lld <- global=%d, current %d\n",
 		  engine->name,
 		  request->fence.context, request->fence.seqno,
 		  request->global_seqno,
-		  hwsp_seqno(request),
-		  intel_engine_get_seqno(engine));
+		  hwsp_seqno(request));
 
 	GEM_BUG_ON(!irqs_disabled());
 	lockdep_assert_held(&engine->timeline.lock);
@@ -425,7 +419,6 @@ void __i915_request_unsubmit(struct i915_request *request)
 	 */
 	GEM_BUG_ON(!request->global_seqno);
 	GEM_BUG_ON(request->global_seqno != engine->timeline.seqno);
-	GEM_BUG_ON(intel_engine_has_completed(engine, request->global_seqno));
 	engine->timeline.seqno--;
 
 	/* We may be recursing from the signal callback of another i915 fence */

drivers/gpu/drm/i915/i915_reset.c

@@ -788,7 +788,6 @@ static void nop_submit_request(struct i915_request *request)
 	spin_lock_irqsave(&engine->timeline.lock, flags);
 	__i915_request_submit(request);
 	i915_request_mark_complete(request);
-	intel_engine_write_global_seqno(engine, request->global_seqno);
 	spin_unlock_irqrestore(&engine->timeline.lock, flags);
 
 	intel_engine_queue_breadcrumbs(engine);

drivers/gpu/drm/i915/intel_engine_cs.c

@@ -455,12 +455,6 @@ int intel_engines_init(struct drm_i915_private *dev_priv)
 	return err;
 }
 
-void intel_engine_write_global_seqno(struct intel_engine_cs *engine, u32 seqno)
-{
-	intel_write_status_page(engine, I915_GEM_HWS_INDEX, seqno);
-	GEM_BUG_ON(intel_engine_get_seqno(engine) != seqno);
-}
-
 static void intel_engine_init_batch_pool(struct intel_engine_cs *engine)
 {
 	i915_gem_batch_pool_init(&engine->batch_pool, engine);
@@ -1011,10 +1005,6 @@ bool intel_engine_is_idle(struct intel_engine_cs *engine)
 	if (i915_reset_failed(engine->i915))
 		return true;
 
-	/* Any inflight/incomplete requests? */
-	if (!intel_engine_signaled(engine, intel_engine_last_submit(engine)))
-		return false;
-
 	/* Waiting to drain ELSP? */
 	if (READ_ONCE(engine->execlists.active)) {
 		struct tasklet_struct *t = &engine->execlists.tasklet;
@@ -1497,9 +1487,7 @@ void intel_engine_dump(struct intel_engine_cs *engine,
 	if (i915_reset_failed(engine->i915))
 		drm_printf(m, "*** WEDGED ***\n");
 
-	drm_printf(m, "\tcurrent seqno %x, last %x, hangcheck %x/%x [%d ms]\n",
-		   intel_engine_get_seqno(engine),
-		   intel_engine_last_submit(engine),
+	drm_printf(m, "\tHangcheck %x:%x [%d ms]\n",
 		   engine->hangcheck.last_seqno,
 		   engine->hangcheck.next_seqno,
 		   jiffies_to_msecs(jiffies - engine->hangcheck.action_timestamp));

drivers/gpu/drm/i915/intel_lrc.c

@@ -528,13 +528,12 @@ static void execlists_submit_ports(struct intel_engine_cs *engine)
 			desc = execlists_update_context(rq);
 			GEM_DEBUG_EXEC(port[n].context_id = upper_32_bits(desc));
 
-			GEM_TRACE("%s in[%d]:  ctx=%d.%d, global=%d (fence %llx:%lld) (current %d:%d), prio=%d\n",
+			GEM_TRACE("%s in[%d]:  ctx=%d.%d, global=%d (fence %llx:%lld) (current %d), prio=%d\n",
 				  engine->name, n,
 				  port[n].context_id, count,
 				  rq->global_seqno,
 				  rq->fence.context, rq->fence.seqno,
 				  hwsp_seqno(rq),
-				  intel_engine_get_seqno(engine),
 				  rq_prio(rq));
 		} else {
 			GEM_BUG_ON(!n);
@@ -840,13 +839,12 @@ execlists_cancel_port_requests(struct intel_engine_execlists * const execlists)
 	while (num_ports-- && port_isset(port)) {
 		struct i915_request *rq = port_request(port);
 
-		GEM_TRACE("%s:port%u global=%d (fence %llx:%lld), (current %d:%d)\n",
+		GEM_TRACE("%s:port%u global=%d (fence %llx:%lld), (current %d)\n",
 			  rq->engine->name,
 			  (unsigned int)(port - execlists->port),
 			  rq->global_seqno,
 			  rq->fence.context, rq->fence.seqno,
-			  hwsp_seqno(rq),
-			  intel_engine_get_seqno(rq->engine));
+			  hwsp_seqno(rq));
 
 		GEM_BUG_ON(!execlists->active);
 		execlists_context_schedule_out(rq,
@@ -902,8 +900,7 @@ static void execlists_cancel_requests(struct intel_engine_cs *engine)
 	struct rb_node *rb;
 	unsigned long flags;
 
-	GEM_TRACE("%s current %d\n",
-		  engine->name, intel_engine_get_seqno(engine));
+	GEM_TRACE("%s\n", engine->name);
 
 	/*
 	 * Before we call engine->cancel_requests(), we should have exclusive
@@ -952,10 +949,6 @@ static void execlists_cancel_requests(struct intel_engine_cs *engine)
 			kmem_cache_free(engine->i915->priorities, p);
 	}
 
-	intel_write_status_page(engine,
-				I915_GEM_HWS_INDEX,
-				intel_engine_last_submit(engine));
-
 	/* Remaining _unready_ requests will be nop'ed when submitted */
 
 	execlists->queue_priority_hint = INT_MIN;
@@ -1071,14 +1064,13 @@ static void process_csb(struct intel_engine_cs *engine)
 						EXECLISTS_ACTIVE_USER));
 
 		rq = port_unpack(port, &count);
-		GEM_TRACE("%s out[0]: ctx=%d.%d, global=%d (fence %llx:%lld) (current %d:%d), prio=%d\n",
+		GEM_TRACE("%s out[0]: ctx=%d.%d, global=%d (fence %llx:%lld) (current %d), prio=%d\n",
 			  engine->name,
 			  port->context_id, count,
 			  rq ? rq->global_seqno : 0,
 			  rq ? rq->fence.context : 0,
 			  rq ? rq->fence.seqno : 0,
 			  rq ? hwsp_seqno(rq) : 0,
-			  intel_engine_get_seqno(engine),
 			  rq ? rq_prio(rq) : 0);
 
 		/* Check the context/desc id for this event matches */
@@ -1946,10 +1938,9 @@ static void execlists_reset(struct intel_engine_cs *engine, bool stalled)
 	/* Following the reset, we need to reload the CSB read/write pointers */
 	reset_csb_pointers(&engine->execlists);
 
-	GEM_TRACE("%s seqno=%d, current=%d, stalled? %s\n",
+	GEM_TRACE("%s seqno=%d, stalled? %s\n",
 		  engine->name,
 		  rq ? rq->global_seqno : 0,
-		  intel_engine_get_seqno(engine),
 		  yesno(stalled));
 	if (!rq)
 		goto out_unlock;

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -782,10 +782,9 @@ static void reset_ring(struct intel_engine_cs *engine, bool stalled)
 		}
 	}
 
-	GEM_TRACE("%s seqno=%d, current=%d, stalled? %s\n",
+	GEM_TRACE("%s seqno=%d, stalled? %s\n",
 		  engine->name,
 		  rq ? rq->global_seqno : 0,
-		  intel_engine_get_seqno(engine),
 		  yesno(stalled));
 	/*
 	 * The guilty request will get skipped on a hung engine.
@@ -924,10 +923,6 @@ static void cancel_requests(struct intel_engine_cs *engine)
 		i915_request_mark_complete(request);
 	}
 
-	intel_write_status_page(engine,
-				I915_GEM_HWS_INDEX,
-				intel_engine_last_submit(engine));
-
 	/* Remaining _unready_ requests will be nop'ed when submitted */
 
 	spin_unlock_irqrestore(&engine->timeline.lock, flags);

drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -848,8 +848,6 @@ __intel_ring_space(unsigned int head, unsigned int tail, unsigned int size)
 	return (head - tail - CACHELINE_BYTES) & (size - 1);
 }
 
-void intel_engine_write_global_seqno(struct intel_engine_cs *engine, u32 seqno);
-
 int intel_engine_setup_common(struct intel_engine_cs *engine);
 int intel_engine_init_common(struct intel_engine_cs *engine);
 void intel_engine_cleanup_common(struct intel_engine_cs *engine);
@@ -867,44 +865,6 @@ void intel_engine_set_hwsp_writemask(struct intel_engine_cs *engine, u32 mask);
 u64 intel_engine_get_active_head(const struct intel_engine_cs *engine);
 u64 intel_engine_get_last_batch_head(const struct intel_engine_cs *engine);
 
-static inline u32 intel_engine_last_submit(struct intel_engine_cs *engine)
-{
-	/*
-	 * We are only peeking at the tail of the submit queue (and not the
-	 * queue itself) in order to gain a hint as to the current active
-	 * state of the engine. Callers are not expected to be taking
-	 * engine->timeline->lock, nor are they expected to be concerned
-	 * wtih serialising this hint with anything, so document it as
-	 * a hint and nothing more.
-	 */
-	return READ_ONCE(engine->timeline.seqno);
-}
-
-static inline u32 intel_engine_get_seqno(struct intel_engine_cs *engine)
-{
-	return intel_read_status_page(engine, I915_GEM_HWS_INDEX);
-}
-
-static inline bool intel_engine_signaled(struct intel_engine_cs *engine,
-					 u32 seqno)
-{
-	return i915_seqno_passed(intel_engine_get_seqno(engine), seqno);
-}
-
-static inline bool intel_engine_has_completed(struct intel_engine_cs *engine,
-					      u32 seqno)
-{
-	GEM_BUG_ON(!seqno);
-	return intel_engine_signaled(engine, seqno);
-}
-
-static inline bool intel_engine_has_started(struct intel_engine_cs *engine,
-					    u32 seqno)
-{
-	GEM_BUG_ON(!seqno);
-	return intel_engine_signaled(engine, seqno - 1);
-}
-
 void intel_engine_get_instdone(struct intel_engine_cs *engine,
 			       struct intel_instdone *instdone);
 

drivers/gpu/drm/i915/selftests/i915_request.c

@@ -226,8 +226,7 @@ static int igt_request_rewind(void *arg)
 	mutex_unlock(&i915->drm.struct_mutex);
 
 	if (i915_request_wait(vip, 0, HZ) == -ETIME) {
-		pr_err("timed out waiting for high priority request, vip.seqno=%d, current seqno=%d\n",
-		       vip->global_seqno, intel_engine_get_seqno(i915->engine[RCS]));
+		pr_err("timed out waiting for high priority request\n");
 		goto err;
 	}
 

drivers/gpu/drm/i915/selftests/mock_engine.c

@@ -86,8 +86,6 @@ static struct mock_request *first_request(struct mock_engine *engine)
 static void advance(struct mock_request *request)
 {
 	list_del_init(&request->link);
-	intel_engine_write_global_seqno(request->base.engine,
-					request->base.global_seqno);
 	i915_request_mark_complete(&request->base);
 	GEM_BUG_ON(!i915_request_completed(&request->base));
 
@@ -278,7 +276,6 @@ void mock_engine_flush(struct intel_engine_cs *engine)
 
 void mock_engine_reset(struct intel_engine_cs *engine)
 {
-	intel_engine_write_global_seqno(engine, 0);
 }
 
 void mock_engine_free(struct intel_engine_cs *engine)