drm/i915: Remove i915_request.global_seqno

Having weaned the interrupt handling off using a single global execution
queue, we no longer need to emit a global_seqno. Note that we still have
a few assumptions about execution order along engine timelines, but this
removes the most obvious artefact!

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/20190226094922.31617-3-chris@chris-wilson.co.uk

12 files changed, 32 insertions, 194 deletions

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 061a767e3bed..fa86c60fb56c 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -380,19 +380,16 @@ static void print_error_buffers(struct drm_i915_error_state_buf *m,
 	err_printf(m, "%s [%d]:\n", name, count);
 
 	while (count--) {
-		err_printf(m, "    %08x_%08x %8u %02x %02x %02x",
+		err_printf(m, "    %08x_%08x %8u %02x %02x",
 			   upper_32_bits(err->gtt_offset),
 			   lower_32_bits(err->gtt_offset),
 			   err->size,
 			   err->read_domains,
-			   err->write_domain,
-			   err->wseqno);
+			   err->write_domain);
 		err_puts(m, tiling_flag(err->tiling));
 		err_puts(m, dirty_flag(err->dirty));
 		err_puts(m, purgeable_flag(err->purgeable));
 		err_puts(m, err->userptr ? " userptr" : "");
-		err_puts(m, err->engine != -1 ? " " : "");
-		err_puts(m, engine_name(m->i915, err->engine));
 		err_puts(m, i915_cache_level_str(m->i915, err->cache_level));
 
 		if (err->name)
@@ -1048,27 +1045,6 @@ i915_error_object_create(struct drm_i915_private *i915,
 	return dst;
 }
 
-/* The error capture is special as tries to run underneath the normal
- * locking rules - so we use the raw version of the i915_active_request lookup.
- */
-static inline u32
-__active_get_seqno(struct i915_active_request *active)
-{
-	struct i915_request *request;
-
-	request = __i915_active_request_peek(active);
-	return request ? request->global_seqno : 0;
-}
-
-static inline int
-__active_get_engine_id(struct i915_active_request *active)
-{
-	struct i915_request *request;
-
-	request = __i915_active_request_peek(active);
-	return request ? request->engine->id : -1;
-}
-
 static void capture_bo(struct drm_i915_error_buffer *err,
 		       struct i915_vma *vma)
 {
@@ -1077,9 +1053,6 @@ static void capture_bo(struct drm_i915_error_buffer *err,
 	err->size = obj->base.size;
 	err->name = obj->base.name;
 
-	err->wseqno = __active_get_seqno(&obj->frontbuffer_write);
-	err->engine = __active_get_engine_id(&obj->frontbuffer_write);
-
 	err->gtt_offset = vma->node.start;
 	err->read_domains = obj->read_domains;
 	err->write_domain = obj->write_domain;
@@ -1284,7 +1257,8 @@ static void record_request(struct i915_request *request,
 	struct i915_gem_context *ctx = request->gem_context;
 
 	erq->flags = request->fence.flags;
-	erq->context = ctx->hw_id;
+	erq->context = request->fence.context;
+	erq->seqno = request->fence.seqno;
 	erq->sched_attr = request->sched.attr;
 	erq->jiffies = request->emitted_jiffies;
 	erq->start = i915_ggtt_offset(request->ring->vma);
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.h b/drivers/gpu/drm/i915/i915_gpu_error.h
index 19ac102afaff..8c1569c1830d 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.h
+++ b/drivers/gpu/drm/i915/i915_gpu_error.h
@@ -164,7 +164,6 @@ struct i915_gpu_state {
 	struct drm_i915_error_buffer {
 		u32 size;
 		u32 name;
-		u32 wseqno;
 		u64 gtt_offset;
 		u32 read_domains;
 		u32 write_domain;
@@ -173,7 +172,6 @@ struct i915_gpu_state {
 		u32 dirty:1;
 		u32 purgeable:1;
 		u32 userptr:1;
-		s32 engine:4;
 		u32 cache_level:3;
 	} *active_bo[I915_NUM_ENGINES], *pinned_bo;
 	u32 active_bo_count[I915_NUM_ENGINES], pinned_bo_count;
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 596183f35b78..935db5548f80 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -179,10 +179,9 @@ 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\n",
+	GEM_TRACE("%s(%s) fence %llx:%lld, current %d\n",
 		  __func__, engine->name,
 		  rq->fence.context, rq->fence.seqno,
-		  rq->global_seqno,
 		  hwsp_seqno(rq));
 
 	GEM_BUG_ON(!i915_request_completed(rq));
@@ -242,10 +241,9 @@ 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\n",
+	GEM_TRACE("%s fence %llx:%lld, current %d\n",
 		  request->engine->name,
 		  request->fence.context, request->fence.seqno,
-		  request->global_seqno,
 		  hwsp_seqno(request));
 
 	lockdep_assert_held(&request->i915->drm.struct_mutex);
@@ -303,10 +301,9 @@ 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\n",
+	GEM_TRACE("%s fence %llx:%lld, current %d\n",
 		  rq->engine->name,
 		  rq->fence.context, rq->fence.seqno,
-		  rq->global_seqno,
 		  hwsp_seqno(rq));
 
 	lockdep_assert_held(&rq->i915->drm.struct_mutex);
@@ -339,22 +336,13 @@ static void move_to_timeline(struct i915_request *request,
 	spin_unlock(&request->timeline->lock);
 }
 
-static u32 next_global_seqno(struct i915_timeline *tl)
-{
-	if (!++tl->seqno)
-		++tl->seqno;
-	return tl->seqno;
-}
-
 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\n",
+	GEM_TRACE("%s fence %llx:%lld -> current %d\n",
 		  engine->name,
 		  request->fence.context, request->fence.seqno,
-		  engine->timeline.seqno + 1,
 		  hwsp_seqno(request));
 
 	GEM_BUG_ON(!irqs_disabled());
@@ -363,16 +351,10 @@ void __i915_request_submit(struct i915_request *request)
 	if (i915_gem_context_is_banned(request->gem_context))
 		i915_request_skip(request, -EIO);
 
-	GEM_BUG_ON(request->global_seqno);
-
-	seqno = next_global_seqno(&engine->timeline);
-	GEM_BUG_ON(!seqno);
-
 	/* We may be recursing from the signal callback of another i915 fence */
 	spin_lock_nested(&request->lock, SINGLE_DEPTH_NESTING);
 	GEM_BUG_ON(test_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags));
 	set_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags);
-	request->global_seqno = seqno;
 	if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &request->fence.flags) &&
 	    !i915_request_enable_breadcrumb(request))
 		intel_engine_queue_breadcrumbs(engine);
@@ -404,10 +386,9 @@ 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\n",
+	GEM_TRACE("%s fence %llx:%lld, current %d\n",
 		  engine->name,
 		  request->fence.context, request->fence.seqno,
-		  request->global_seqno,
 		  hwsp_seqno(request));
 
 	GEM_BUG_ON(!irqs_disabled());
@@ -417,13 +398,9 @@ void __i915_request_unsubmit(struct i915_request *request)
 	 * Only unwind in reverse order, required so that the per-context list
 	 * is kept in seqno/ring order.
 	 */
-	GEM_BUG_ON(!request->global_seqno);
-	GEM_BUG_ON(request->global_seqno != engine->timeline.seqno);
-	engine->timeline.seqno--;
 
 	/* We may be recursing from the signal callback of another i915 fence */
 	spin_lock_nested(&request->lock, SINGLE_DEPTH_NESTING);
-	request->global_seqno = 0;
 	if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &request->fence.flags))
 		i915_request_cancel_breadcrumb(request);
 	GEM_BUG_ON(!test_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags));
@@ -637,7 +614,6 @@ i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx)
 	i915_sched_node_init(&rq->sched);
 
 	/* No zalloc, must clear what we need by hand */
-	rq->global_seqno = 0;
 	rq->file_priv = NULL;
 	rq->batch = NULL;
 	rq->capture_list = NULL;
diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
index 40f3e8dcbdd5..1e127c1c53fa 100644
--- a/drivers/gpu/drm/i915/i915_request.h
+++ b/drivers/gpu/drm/i915/i915_request.h
@@ -147,14 +147,6 @@ struct i915_request {
 	 */
 	const u32 *hwsp_seqno;
 
-	/**
-	 * GEM sequence number associated with this request on the
-	 * global execution timeline. It is zero when the request is not
-	 * on the HW queue (i.e. not on the engine timeline list).
-	 * Its value is guarded by the timeline spinlock.
-	 */
-	u32 global_seqno;
-
 	/** Position in the ring of the start of the request */
 	u32 head;
 
@@ -247,30 +239,6 @@ i915_request_put(struct i915_request *rq)
 	dma_fence_put(&rq->fence);
 }
 
-/**
- * i915_request_global_seqno - report the current global seqno
- * @request - the request
- *
- * A request is assigned a global seqno only when it is on the hardware
- * execution queue. The global seqno can be used to maintain a list of
- * requests on the same engine in retirement order, for example for
- * constructing a priority queue for waiting. Prior to its execution, or
- * if it is subsequently removed in the event of preemption, its global
- * seqno is zero. As both insertion and removal from the execution queue
- * may operate in IRQ context, it is not guarded by the usual struct_mutex
- * BKL. Instead those relying on the global seqno must be prepared for its
- * value to change between reads. Only when the request is complete can
- * the global seqno be stable (due to the memory barriers on submitting
- * the commands to the hardware to write the breadcrumb, if the HWS shows
- * that it has passed the global seqno and the global seqno is unchanged
- * after the read, it is indeed complete).
- */
-static inline u32
-i915_request_global_seqno(const struct i915_request *request)
-{
-	return READ_ONCE(request->global_seqno);
-}
-
 int i915_request_await_object(struct i915_request *to,
 			      struct drm_i915_gem_object *obj,
 			      bool write);
diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
index 0d9cedb892b0..12893304c8f8 100644
--- a/drivers/gpu/drm/i915/i915_trace.h
+++ b/drivers/gpu/drm/i915/i915_trace.h
@@ -708,7 +708,6 @@ DECLARE_EVENT_CLASS(i915_request,
 			     __field(u16, class)
 			     __field(u16, instance)
 			     __field(u32, seqno)
-			     __field(u32, global)
 			     ),
 
 	    TP_fast_assign(
@@ -718,13 +717,11 @@ DECLARE_EVENT_CLASS(i915_request,
 			   __entry->instance = rq->engine->instance;
 			   __entry->ctx = rq->fence.context;
 			   __entry->seqno = rq->fence.seqno;
-			   __entry->global = rq->global_seqno;
 			   ),
 
-	    TP_printk("dev=%u, engine=%u:%u, hw_id=%u, ctx=%llu, seqno=%u, global=%u",
+	    TP_printk("dev=%u, engine=%u:%u, hw_id=%u, ctx=%llu, seqno=%u",
 		      __entry->dev, __entry->class, __entry->instance,
-		      __entry->hw_id, __entry->ctx, __entry->seqno,
-		      __entry->global)
+		      __entry->hw_id, __entry->ctx, __entry->seqno)
 );
 
 DEFINE_EVENT(i915_request, i915_request_add,
@@ -754,7 +751,6 @@ TRACE_EVENT(i915_request_in,
 			     __field(u16, class)
 			     __field(u16, instance)
 			     __field(u32, seqno)
-			     __field(u32, global_seqno)
 			     __field(u32, port)
 			     __field(u32, prio)
 			    ),
@@ -766,15 +762,14 @@ TRACE_EVENT(i915_request_in,
 			   __entry->instance = rq->engine->instance;
 			   __entry->ctx = rq->fence.context;
 			   __entry->seqno = rq->fence.seqno;
-			   __entry->global_seqno = rq->global_seqno;
 			   __entry->prio = rq->sched.attr.priority;
 			   __entry->port = port;
 			   ),
 
-	    TP_printk("dev=%u, engine=%u:%u, hw_id=%u, ctx=%llu, seqno=%u, prio=%u, global=%u, port=%u",
+	    TP_printk("dev=%u, engine=%u:%u, hw_id=%u, ctx=%llu, seqno=%u, prio=%u, port=%u",
 		      __entry->dev, __entry->class, __entry->instance,
 		      __entry->hw_id, __entry->ctx, __entry->seqno,
-		      __entry->prio, __entry->global_seqno, __entry->port)
+		      __entry->prio, __entry->port)
 );
 
 TRACE_EVENT(i915_request_out,
@@ -788,7 +783,6 @@ TRACE_EVENT(i915_request_out,
 			     __field(u16, class)
 			     __field(u16, instance)
 			     __field(u32, seqno)
-			     __field(u32, global_seqno)
 			     __field(u32, completed)
 			    ),
 
@@ -799,14 +793,13 @@ TRACE_EVENT(i915_request_out,
 			   __entry->instance = rq->engine->instance;
 			   __entry->ctx = rq->fence.context;
 			   __entry->seqno = rq->fence.seqno;
-			   __entry->global_seqno = rq->global_seqno;
 			   __entry->completed = i915_request_completed(rq);
 			   ),
 
-		    TP_printk("dev=%u, engine=%u:%u, hw_id=%u, ctx=%llu, seqno=%u, global=%u, completed?=%u",
+		    TP_printk("dev=%u, engine=%u:%u, hw_id=%u, ctx=%llu, seqno=%u, completed?=%u",
 			      __entry->dev, __entry->class, __entry->instance,
 			      __entry->hw_id, __entry->ctx, __entry->seqno,
-			      __entry->global_seqno, __entry->completed)
+			      __entry->completed)
 );
 
 #else
@@ -849,7 +842,6 @@ TRACE_EVENT(i915_request_wait_begin,
 			     __field(u16, class)
 			     __field(u16, instance)
 			     __field(u32, seqno)
-			     __field(u32, global)
 			     __field(unsigned int, flags)
 			     ),
 
@@ -866,14 +858,13 @@ TRACE_EVENT(i915_request_wait_begin,
 			   __entry->instance = rq->engine->instance;
 			   __entry->ctx = rq->fence.context;
 			   __entry->seqno = rq->fence.seqno;
-			   __entry->global = rq->global_seqno;
 			   __entry->flags = flags;
 			   ),
 
-	    TP_printk("dev=%u, engine=%u:%u, hw_id=%u, ctx=%llu, seqno=%u, global=%u, blocking=%u, flags=0x%x",
+	    TP_printk("dev=%u, engine=%u:%u, hw_id=%u, ctx=%llu, seqno=%u, blocking=%u, flags=0x%x",
 		      __entry->dev, __entry->class, __entry->instance,
 		      __entry->hw_id, __entry->ctx, __entry->seqno,
-		      __entry->global, !!(__entry->flags & I915_WAIT_LOCKED),
+		      !!(__entry->flags & I915_WAIT_LOCKED),
 		      __entry->flags)
 );
 
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index ec859c7b8c7c..b7b626195eda 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -1271,15 +1271,14 @@ static void print_request(struct drm_printer *m,
 
 	x = print_sched_attr(rq->i915, &rq->sched.attr, buf, x, sizeof(buf));
 
-	drm_printf(m, "%s%x%s%s [%llx:%llx]%s @ %dms: %s\n",
+	drm_printf(m, "%s %llx:%llx%s%s %s @ %dms: %s\n",
 		   prefix,
-		   rq->global_seqno,
+		   rq->fence.context, rq->fence.seqno,
 		   i915_request_completed(rq) ? "!" :
 		   i915_request_started(rq) ? "*" :
 		   "",
 		   test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 			    &rq->fence.flags) ?  "+" : "",
-		   rq->fence.context, rq->fence.seqno,
 		   buf,
 		   jiffies_to_msecs(jiffies - rq->emitted_jiffies),
 		   name);
diff --git a/drivers/gpu/drm/i915/intel_guc_submission.c b/drivers/gpu/drm/i915/intel_guc_submission.c
index 8bc8aa54aa35..20cbceeabeae 100644
--- a/drivers/gpu/drm/i915/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/intel_guc_submission.c
@@ -535,7 +535,7 @@ static void guc_add_request(struct intel_guc *guc, struct i915_request *rq)
 	spin_lock(&client->wq_lock);
 
 	guc_wq_item_append(client, engine->guc_id, ctx_desc,
-			   ring_tail, rq->global_seqno);
+			   ring_tail, rq->fence.seqno);
 	guc_ring_doorbell(client);
 
 	client->submissions[engine->id] += 1;
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 09b56b84e007..c4f4966b0f4f 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -172,12 +172,6 @@ static void execlists_init_reg_state(u32 *reg_state,
 				     struct intel_engine_cs *engine,
 				     struct intel_ring *ring);
 
-static inline u32 intel_hws_seqno_address(struct intel_engine_cs *engine)
-{
-	return (i915_ggtt_offset(engine->status_page.vma) +
-		I915_GEM_HWS_INDEX_ADDR);
-}
-
 static inline u32 intel_hws_hangcheck_address(struct intel_engine_cs *engine)
 {
 	return (i915_ggtt_offset(engine->status_page.vma) +
@@ -528,10 +522,9 @@ 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), prio=%d\n",
+			GEM_TRACE("%s in[%d]:  ctx=%d.%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),
 				  rq_prio(rq));
@@ -839,10 +832,9 @@ 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)\n",
+		GEM_TRACE("%s:port%u 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));
 
@@ -924,8 +916,6 @@ static void execlists_cancel_requests(struct intel_engine_cs *engine)
 
 	/* Mark all executing requests as skipped. */
 	list_for_each_entry(rq, &engine->timeline.requests, link) {
-		GEM_BUG_ON(!rq->global_seqno);
-
 		if (!i915_request_signaled(rq))
 			dma_fence_set_error(&rq->fence, -EIO);
 
@@ -1064,10 +1054,9 @@ 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), prio=%d\n",
+		GEM_TRACE("%s out[0]: ctx=%d.%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,
@@ -1938,10 +1927,7 @@ 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, stalled? %s\n",
-		  engine->name,
-		  rq ? rq->global_seqno : 0,
-		  yesno(stalled));
+	GEM_TRACE("%s stalled? %s\n", engine->name, yesno(stalled));
 	if (!rq)
 		goto out_unlock;
 
@@ -2196,9 +2182,6 @@ static u32 *gen8_emit_wa_tail(struct i915_request *request, u32 *cs)
 
 static u32 *gen8_emit_fini_breadcrumb(struct i915_request *request, u32 *cs)
 {
-	/* w/a: bit 5 needs to be zero for MI_FLUSH_DW address. */
-	BUILD_BUG_ON(I915_GEM_HWS_INDEX_ADDR & (1 << 5));
-
 	cs = gen8_emit_ggtt_write(cs,
 				  request->fence.seqno,
 				  request->timeline->hwsp_offset);
@@ -2207,10 +2190,6 @@ static u32 *gen8_emit_fini_breadcrumb(struct i915_request *request, u32 *cs)
 				  intel_engine_next_hangcheck_seqno(request->engine),
 				  intel_hws_hangcheck_address(request->engine));
 
-	cs = gen8_emit_ggtt_write(cs,
-				  request->global_seqno,
-				  intel_hws_seqno_address(request->engine));
-
 	*cs++ = MI_USER_INTERRUPT;
 	*cs++ = MI_ARB_ON_OFF | MI_ARB_ENABLE;
 
@@ -2236,11 +2215,6 @@ static u32 *gen8_emit_fini_breadcrumb_rcs(struct i915_request *request, u32 *cs)
 				      intel_hws_hangcheck_address(request->engine),
 				      0);
 
-	cs = gen8_emit_ggtt_write_rcs(cs,
-				      request->global_seqno,
-				      intel_hws_seqno_address(request->engine),
-				      PIPE_CONTROL_CS_STALL);
-
 	*cs++ = MI_USER_INTERRUPT;
 	*cs++ = MI_ARB_ON_OFF | MI_ARB_ENABLE;
 
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 2d59e2990448..1b96b0960adc 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -49,12 +49,6 @@ static inline u32 hws_hangcheck_address(struct intel_engine_cs *engine)
 		I915_GEM_HWS_HANGCHECK_ADDR);
 }
 
-static inline u32 intel_hws_seqno_address(struct intel_engine_cs *engine)
-{
-	return (i915_ggtt_offset(engine->status_page.vma) +
-		I915_GEM_HWS_INDEX_ADDR);
-}
-
 unsigned int intel_ring_update_space(struct intel_ring *ring)
 {
 	unsigned int space;
@@ -327,11 +321,6 @@ static u32 *gen6_rcs_emit_breadcrumb(struct i915_request *rq, u32 *cs)
 	*cs++ = hws_hangcheck_address(rq->engine) | PIPE_CONTROL_GLOBAL_GTT;
 	*cs++ = intel_engine_next_hangcheck_seqno(rq->engine);
 
-	*cs++ = GFX_OP_PIPE_CONTROL(4);
-	*cs++ = PIPE_CONTROL_QW_WRITE | PIPE_CONTROL_CS_STALL;
-	*cs++ = intel_hws_seqno_address(rq->engine) | PIPE_CONTROL_GLOBAL_GTT;
-	*cs++ = rq->global_seqno;
-
 	*cs++ = MI_USER_INTERRUPT;
 	*cs++ = MI_NOOP;
 
@@ -438,13 +427,6 @@ static u32 *gen7_rcs_emit_breadcrumb(struct i915_request *rq, u32 *cs)
 	*cs++ = hws_hangcheck_address(rq->engine);
 	*cs++ = intel_engine_next_hangcheck_seqno(rq->engine);
 
-	*cs++ = GFX_OP_PIPE_CONTROL(4);
-	*cs++ = (PIPE_CONTROL_QW_WRITE |
-		 PIPE_CONTROL_GLOBAL_GTT_IVB |
-		 PIPE_CONTROL_CS_STALL);
-	*cs++ = intel_hws_seqno_address(rq->engine);
-	*cs++ = rq->global_seqno;
-
 	*cs++ = MI_USER_INTERRUPT;
 	*cs++ = MI_NOOP;
 
@@ -467,11 +449,8 @@ static u32 *gen6_xcs_emit_breadcrumb(struct i915_request *rq, u32 *cs)
 	*cs++ = I915_GEM_HWS_HANGCHECK_ADDR | MI_FLUSH_DW_USE_GTT;
 	*cs++ = intel_engine_next_hangcheck_seqno(rq->engine);
 
-	*cs++ = MI_FLUSH_DW | MI_FLUSH_DW_OP_STOREDW | MI_FLUSH_DW_STORE_INDEX;
-	*cs++ = I915_GEM_HWS_INDEX_ADDR | MI_FLUSH_DW_USE_GTT;
-	*cs++ = rq->global_seqno;
-
 	*cs++ = MI_USER_INTERRUPT;
+	*cs++ = MI_NOOP;
 
 	rq->tail = intel_ring_offset(rq, cs);
 	assert_ring_tail_valid(rq->ring, rq->tail);
@@ -495,10 +474,6 @@ static u32 *gen7_xcs_emit_breadcrumb(struct i915_request *rq, u32 *cs)
 	*cs++ = I915_GEM_HWS_HANGCHECK_ADDR | MI_FLUSH_DW_USE_GTT;
 	*cs++ = intel_engine_next_hangcheck_seqno(rq->engine);
 
-	*cs++ = MI_FLUSH_DW | MI_FLUSH_DW_OP_STOREDW | MI_FLUSH_DW_STORE_INDEX;
-	*cs++ = I915_GEM_HWS_INDEX_ADDR | MI_FLUSH_DW_USE_GTT;
-	*cs++ = rq->global_seqno;
-
 	for (i = 0; i < GEN7_XCS_WA; i++) {
 		*cs++ = MI_STORE_DWORD_INDEX;
 		*cs++ = I915_GEM_HWS_SEQNO_ADDR;
@@ -510,7 +485,6 @@ static u32 *gen7_xcs_emit_breadcrumb(struct i915_request *rq, u32 *cs)
 	*cs++ = 0;
 
 	*cs++ = MI_USER_INTERRUPT;
-	*cs++ = MI_NOOP;
 
 	rq->tail = intel_ring_offset(rq, cs);
 	assert_ring_tail_valid(rq->ring, rq->tail);
@@ -782,10 +756,8 @@ static void reset_ring(struct intel_engine_cs *engine, bool stalled)
 		}
 	}
 
-	GEM_TRACE("%s seqno=%d, stalled? %s\n",
-		  engine->name,
-		  rq ? rq->global_seqno : 0,
-		  yesno(stalled));
+	GEM_TRACE("%s stalled? %s\n", engine->name, yesno(stalled));
+
 	/*
 	 * The guilty request will get skipped on a hung engine.
 	 *
@@ -915,8 +887,6 @@ static void cancel_requests(struct intel_engine_cs *engine)
 
 	/* Mark all submitted requests as skipped. */
 	list_for_each_entry(request, &engine->timeline.requests, link) {
-		GEM_BUG_ON(!request->global_seqno);
-
 		if (!i915_request_signaled(request))
 			dma_fence_set_error(&request->fence, -EIO);
 
@@ -953,12 +923,7 @@ static u32 *i9xx_emit_breadcrumb(struct i915_request *rq, u32 *cs)
 	*cs++ = I915_GEM_HWS_HANGCHECK_ADDR;
 	*cs++ = intel_engine_next_hangcheck_seqno(rq->engine);
 
-	*cs++ = MI_STORE_DWORD_INDEX;
-	*cs++ = I915_GEM_HWS_INDEX_ADDR;
-	*cs++ = rq->global_seqno;
-
 	*cs++ = MI_USER_INTERRUPT;
-	*cs++ = MI_NOOP;
 
 	rq->tail = intel_ring_offset(rq, cs);
 	assert_ring_tail_valid(rq->ring, rq->tail);
@@ -977,21 +942,18 @@ static u32 *gen5_emit_breadcrumb(struct i915_request *rq, u32 *cs)
 	*cs++ = MI_FLUSH;
 
 	*cs++ = MI_STORE_DWORD_INDEX;
-	*cs++ = I915_GEM_HWS_SEQNO_ADDR;
-	*cs++ = rq->fence.seqno;
-
-	*cs++ = MI_STORE_DWORD_INDEX;
 	*cs++ = I915_GEM_HWS_HANGCHECK_ADDR;
 	*cs++ = intel_engine_next_hangcheck_seqno(rq->engine);
 
 	BUILD_BUG_ON(GEN5_WA_STORES < 1);
 	for (i = 0; i < GEN5_WA_STORES; i++) {
 		*cs++ = MI_STORE_DWORD_INDEX;
-		*cs++ = I915_GEM_HWS_INDEX_ADDR;
-		*cs++ = rq->global_seqno;
+		*cs++ = I915_GEM_HWS_SEQNO_ADDR;
+		*cs++ = rq->fence.seqno;
 	}
 
 	*cs++ = MI_USER_INTERRUPT;
+	*cs++ = MI_NOOP;
 
 	rq->tail = intel_ring_offset(rq, cs);
 	assert_ring_tail_valid(rq->ring, rq->tail);
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 551b3daa741c..de8dba7565b0 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -724,8 +724,6 @@ intel_write_status_page(struct intel_engine_cs *engine, int reg, u32 value)
  *
  * The area from dword 0x30 to 0x3ff is available for driver usage.
  */
-#define I915_GEM_HWS_INDEX		0x30
-#define I915_GEM_HWS_INDEX_ADDR		(I915_GEM_HWS_INDEX * sizeof(u32))
 #define I915_GEM_HWS_PREEMPT		0x32
 #define I915_GEM_HWS_PREEMPT_ADDR	(I915_GEM_HWS_PREEMPT * sizeof(u32))
 #define I915_GEM_HWS_HANGCHECK		0x34
diff --git a/drivers/gpu/drm/i915/selftests/intel_hangcheck.c b/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
index a77e4bf1ab55..fa02cf9ce0cf 100644
--- a/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
+++ b/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
@@ -571,11 +571,10 @@ static int active_request_put(struct i915_request *rq)
 		return 0;
 
 	if (i915_request_wait(rq, 0, 5 * HZ) < 0) {
-		GEM_TRACE("%s timed out waiting for completion of fence %llx:%lld, seqno %d.\n",
+		GEM_TRACE("%s timed out waiting for completion of fence %llx:%lld\n",
 			  rq->engine->name,
 			  rq->fence.context,
-			  rq->fence.seqno,
-			  i915_request_global_seqno(rq));
+			  rq->fence.seqno);
 		GEM_TRACE_DUMP();
 
 		i915_gem_set_wedged(rq->i915);
diff --git a/drivers/gpu/drm/i915/selftests/mock_engine.c b/drivers/gpu/drm/i915/selftests/mock_engine.c
index 79bf27606ab8..6f3fb803c747 100644
--- a/drivers/gpu/drm/i915/selftests/mock_engine.c
+++ b/drivers/gpu/drm/i915/selftests/mock_engine.c
@@ -196,7 +196,6 @@ static void mock_submit_request(struct i915_request *request)
 	unsigned long flags;
 
 	i915_request_submit(request);
-	GEM_BUG_ON(!request->global_seqno);
 
 	spin_lock_irqsave(&engine->hw_lock, flags);
 	list_add_tail(&mock->link, &engine->hw_queue);