[Intel-gfx] [PATCH 63/66] drm/i915/gt: Infrastructure for ring scheduling

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

Build a bare bones scheduler to sit on top the global legacy ringbuffer
submission. This virtual execlists scheme should be applicable to all
older platforms.

A key problem we have with the legacy ring buffer submission is that it
only allows for FIFO queuing. All clients share the global request queue
and must contend for its lock when submitting. As any client may need to
wait for external events, all clients must then wait. However, if we
stage each client into their own virtual ringbuffer with their own
timelines, we can copy the client requests into the global ringbuffer
only when they are ready, reordering the submission around stalls.
Furthermore, the ability to reorder gives us rudimentarily priority
sorting -- although without preemption support, once something is on the
GPU it stays on the GPU, and so it is still possible for a hog to delay
a high priority request (such as updating the display). However, it does
means that in keeping a short submission queue, the high priority
request will be next. This design resembles the old guc submission
scheduler, for reordering requests onto a global workqueue.

The implementation uses the MI_USER_INTERRUPT at the end of every
request to track completion, so is more interrupt happy than execlists
[which has an interrupt for each context event, albeit two]. Our
interrupts on these system are relatively heavy, and in the past we have
been able to completely starve Sandybrige by the interrupt traffic. Our
interrupt handlers are being much better (in part offloading the work to
bottom halves leaving the interrupt itself only dealing with acking the
registers) but we can still see the impact of starvation in the uneven
submission latency on a saturated system.

Overall though, the short sumission queues and extra interrupts do not
appear to be affecting throughput (+-10%, some tasks even improve to the
reduced request overheads) and improve latency. [Which is a massive
improvement since the introduction of Sandybridge!]

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/Makefile                 |   1 +
 drivers/gpu/drm/i915/gt/intel_engine.h        |   1 +
 drivers/gpu/drm/i915/gt/intel_engine_types.h  |   1 +
 .../gpu/drm/i915/gt/intel_ring_scheduler.c    | 762 ++++++++++++++++++
 .../gpu/drm/i915/gt/intel_ring_submission.c   |  13 +-
 .../gpu/drm/i915/gt/intel_ring_submission.h   |  16 +
 6 files changed, 788 insertions(+), 6 deletions(-)
 create mode 100644 drivers/gpu/drm/i915/gt/intel_ring_scheduler.c
 create mode 100644 drivers/gpu/drm/i915/gt/intel_ring_submission.h

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 2cf54db8b847..e4eea4980129 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -110,6 +110,7 @@ gt-y += \
 	gt/intel_renderstate.o \
 	gt/intel_reset.o \
 	gt/intel_ring.o \
+	gt/intel_ring_scheduler.o \
 	gt/intel_ring_submission.o \
 	gt/intel_rps.o \
 	gt/intel_sseu.o \
diff --git a/drivers/gpu/drm/i915/gt/intel_engine.h b/drivers/gpu/drm/i915/gt/intel_engine.h
index dcc2fc22ea37..b816581b95d3 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine.h
@@ -209,6 +209,7 @@ void intel_engine_cleanup_common(struct intel_engine_cs *engine);
 int intel_engine_resume(struct intel_engine_cs *engine);
 
 int intel_ring_submission_setup(struct intel_engine_cs *engine);
+int intel_ring_scheduler_setup(struct intel_engine_cs *engine);
 
 int intel_engine_stop_cs(struct intel_engine_cs *engine);
 void intel_engine_cancel_stop_cs(struct intel_engine_cs *engine);
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
index 8c502cf34de7..78a57879aef8 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
@@ -339,6 +339,7 @@ struct intel_engine_cs {
 	struct {
 		struct intel_ring *ring;
 		struct intel_timeline *timeline;
+		struct intel_context *context;
 	} legacy;
 
 	/*
diff --git a/drivers/gpu/drm/i915/gt/intel_ring_scheduler.c b/drivers/gpu/drm/i915/gt/intel_ring_scheduler.c
new file mode 100644
index 000000000000..d3c22037f17d
--- /dev/null
+++ b/drivers/gpu/drm/i915/gt/intel_ring_scheduler.c
@@ -0,0 +1,762 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2020 Intel Corporation
+ */
+
+#include <linux/log2.h>
+
+#include <drm/i915_drm.h>
+
+#include "mm/i915_acquire_ctx.h"
+
+#include "i915_drv.h"
+#include "intel_context.h"
+#include "intel_engine_stats.h"
+#include "intel_gt.h"
+#include "intel_gt_pm.h"
+#include "intel_gt_requests.h"
+#include "intel_reset.h"
+#include "intel_ring.h"
+#include "intel_ring_submission.h"
+#include "shmem_utils.h"
+
+/*
+ * Rough estimate of the typical request size, performing a flush,
+ * set-context and then emitting the batch.
+ */
+#define LEGACY_REQUEST_SIZE 200
+
+static inline int rq_prio(const struct i915_request *rq)
+{
+	return rq->sched.attr.priority;
+}
+
+static inline u64 rq_deadline(const struct i915_request *rq)
+{
+	return rq->sched.deadline;
+}
+
+static inline struct i915_priolist *to_priolist(struct rb_node *rb)
+{
+	return rb_entry(rb, struct i915_priolist, node);
+}
+
+static inline bool reset_in_progress(const struct intel_engine_execlists *el)
+{
+	return unlikely(!__tasklet_is_enabled(&el->tasklet));
+}
+
+static void
+set_current_context(struct intel_context **ptr, struct intel_context *ce)
+{
+	if (ce)
+		intel_context_get(ce);
+
+	ce = xchg(ptr, ce);
+
+	if (ce)
+		intel_context_put(ce);
+}
+
+static void schedule_in(struct intel_engine_cs *engine, struct i915_request *rq)
+{
+	__intel_gt_pm_get(engine->gt);
+	intel_engine_context_in(engine);
+	i915_request_get(rq);
+}
+
+static void schedule_in_new(struct intel_engine_cs *engine,
+			    struct i915_request **port)
+{
+	while (*port)
+		schedule_in(engine, *port++);
+}
+
+static void schedule_out(struct i915_request *rq)
+{
+	struct intel_engine_cs *engine = rq->engine;
+	struct intel_context *ce = rq->context;
+
+	if (i915_request_completed(rq)) {
+		if (!list_is_last_rcu(&rq->link, &ce->timeline->requests))
+			i915_request_update_deadline(list_next_entry(rq, link));
+		else
+			intel_engine_add_retire(engine, ce->timeline);
+	}
+
+	i915_request_put(rq);
+	intel_engine_context_out(engine);
+	intel_gt_pm_put_async(engine->gt);
+}
+
+static inline void *clear_ports(struct i915_request **ports, int count)
+{
+	return memset_p((void **)ports, NULL, count);
+}
+
+static u32 *ring_map(struct intel_ring *ring, u32 len)
+{
+	u32 *va;
+
+	if (unlikely(ring->tail + len > ring->effective_size)) {
+		memset(ring->vaddr + ring->tail, 0, ring->size - ring->tail);
+		ring->tail = 0;
+	}
+
+	va = ring->vaddr + ring->tail;
+	ring->tail = intel_ring_wrap(ring, ring->tail + len);
+
+	return va;
+}
+
+static inline u32 *ring_map_dw(struct intel_ring *ring, u32 len)
+{
+	return ring_map(ring, len * sizeof(u32));
+}
+
+static void ring_copy(struct intel_ring *dst,
+		      const struct intel_ring *src,
+		      u32 start, u32 end)
+{
+	unsigned int len;
+	void *out;
+
+	len = end - start;
+	if (end < start)
+		len += src->size;
+	out = ring_map(dst, len);
+
+	if (end < start) {
+		len = src->size - start;
+		memcpy(out, src->vaddr + start, len);
+		out += len;
+		start = 0;
+	}
+
+	memcpy(out, src->vaddr + start, end - start);
+}
+
+static void switch_context(struct intel_ring *ring, struct i915_request *rq)
+{
+}
+
+static struct i915_request *ring_submit(struct i915_request *rq)
+{
+	struct intel_ring *ring = rq->engine->legacy.ring;
+
+	__i915_request_submit(rq);
+
+	if (rq->engine->legacy.context != rq->context) {
+		switch_context(ring, rq);
+		set_current_context(&rq->engine->legacy.context, rq->context);
+	}
+
+	ring_copy(ring, rq->ring, rq->head, rq->tail);
+	return rq;
+}
+
+static struct i915_request **
+copy_active(struct i915_request **port, struct i915_request * const *active)
+{
+	while (*active)
+		*port++ = *active++;
+
+	return port;
+}
+
+static void dequeue(struct intel_engine_cs *engine)
+{
+	struct intel_engine_execlists * const el = &engine->execlists;
+	struct i915_request ** const last_port = el->pending + el->port_mask;
+	struct i915_request **port, **first;
+	unsigned long flags;
+	struct rb_node *rb;
+
+	first = copy_active(el->pending, el->active);
+	if (first > last_port)
+		return;
+
+	port = first;
+	*port = NULL;
+	spin_lock_irqsave(&engine->active.lock, flags);
+	while ((rb = rb_first_cached(&el->queue))) {
+		struct i915_priolist *p = to_priolist(rb);
+		struct i915_request *rq, *rn;
+
+		priolist_for_each_request_consume(rq, rn, p) {
+			GEM_BUG_ON(rq == *port);
+			if (*port && rq->context != (*port)->context) {
+				if (port == last_port)
+					goto done;
+
+				port++;
+			}
+
+			*port = ring_submit(rq);
+		}
+
+		rb_erase_cached(&p->node, &el->queue);
+		i915_priolist_free(p);
+	}
+done:
+	spin_unlock_irqrestore(&engine->active.lock, flags);
+	if (!*port)
+		return;
+
+	*++port = NULL;
+	schedule_in_new(engine, first);
+	WRITE_ONCE(el->active, el->pending);
+
+	wmb(); /* paranoid flush of WCB before RING_TAIL write */
+	ENGINE_WRITE(engine, RING_TAIL, engine->legacy.ring->tail);
+	memcpy(el->inflight, el->pending,
+	       (port - el->pending + 1) * sizeof(*port));
+
+	WRITE_ONCE(el->active, el->inflight);
+	GEM_BUG_ON(!*el->active);
+}
+
+static struct i915_request **
+process_q(struct intel_engine_cs *engine, struct i915_request **inactive)
+{
+	struct intel_engine_execlists * const el = &engine->execlists;
+
+	while (*el->active) {
+		if (!i915_request_completed(*el->active))
+			break;
+
+		*inactive++ = *el->active++;
+	}
+
+	return inactive;
+}
+
+static void post_process_q(struct i915_request **port,
+			   struct i915_request * const *inactive)
+{
+	while (port != inactive)
+		schedule_out(*port++);
+}
+
+static void submission_tasklet(unsigned long data)
+{
+	struct intel_engine_cs *engine = (struct intel_engine_cs *)data;
+	struct i915_request *post[EXECLIST_MAX_PORTS];
+	struct i915_request **inactive;
+
+	inactive = process_q(engine, post);
+	GEM_BUG_ON(inactive - post > ARRAY_SIZE(post));
+
+	if (rb_first_cached(&engine->execlists.queue))
+		dequeue(engine);
+
+	post_process_q(post, inactive);
+}
+
+static void submit_request(struct i915_request *rq)
+{
+	struct intel_engine_cs *engine = rq->engine;
+	unsigned long flags;
+
+	spin_lock_irqsave(&engine->active.lock, flags);
+	if (intel_engine_queue_request(engine, rq))
+		tasklet_hi_schedule(&engine->execlists.tasklet);
+	spin_unlock_irqrestore(&engine->active.lock, flags);
+}
+
+static void reset_prepare(struct intel_engine_cs *engine)
+{
+	struct intel_engine_execlists * const el = &engine->execlists;
+
+	GEM_TRACE("%s\n", engine->name);
+
+	__tasklet_disable_sync_once(&el->tasklet);
+	GEM_BUG_ON(!reset_in_progress(el));
+
+	intel_ring_submission_reset_prepare(engine);
+}
+
+static struct i915_request *
+__unwind_incomplete_requests(struct intel_engine_cs *engine)
+{
+	struct i915_request *rq, *rn, *active = NULL;
+	struct list_head *uninitialized_var(pl);
+	u64 deadline = I915_DEADLINE_NEVER;
+
+	lockdep_assert_held(&engine->active.lock);
+
+	list_for_each_entry_safe_reverse(rq, rn,
+					 &engine->active.requests,
+					 sched.link) {
+		if (i915_request_completed(rq))
+			break;
+
+		__i915_request_unsubmit(rq);
+
+		if (i915_request_started(rq)) {
+			u64 deadline =
+				i915_scheduler_next_virtual_deadline(rq_prio(rq));
+			rq->sched.deadline = min(rq_deadline(rq), deadline);
+		}
+
+		if (rq_deadline(rq) != deadline) {
+			deadline = rq_deadline(rq);
+			pl = i915_sched_lookup_priolist(engine, deadline);
+		}
+		GEM_BUG_ON(RB_EMPTY_ROOT(&engine->execlists.queue.rb_root));
+
+		list_move(&rq->sched.link, pl);
+		set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
+
+		active = rq;
+	}
+
+	return active;
+}
+
+static void cancel_port_requests(struct intel_engine_cs *engine)
+{
+	struct intel_engine_execlists * const el = &engine->execlists;
+	struct i915_request * const *port;
+
+	clear_ports(el->pending, ARRAY_SIZE(el->pending));
+	for (port = xchg(&el->active, el->pending); *port; port++)
+		schedule_out(*port);
+	clear_ports(el->inflight, ARRAY_SIZE(el->inflight));
+
+	smp_wmb(); /* complete the seqlock for execlists_active() */
+	WRITE_ONCE(el->active, el->inflight);
+}
+
+static void __ring_rewind(struct intel_engine_cs *engine, bool stalled)
+{
+	struct i915_request *rq;
+
+	rq = __unwind_incomplete_requests(engine);
+	if (rq && i915_request_started(rq))
+		__i915_request_reset(rq, stalled);
+
+	/* Clear the global submission state, we will submit from scratch */
+	intel_ring_reset(engine->legacy.ring, 0);
+	set_current_context(&engine->legacy.context, NULL);
+}
+
+static void ring_reset_rewind(struct intel_engine_cs *engine, bool stalled)
+{
+	unsigned long flags;
+
+	cancel_port_requests(engine);
+
+	spin_lock_irqsave(&engine->active.lock, flags);
+	__ring_rewind(engine, stalled);
+	spin_unlock_irqrestore(&engine->active.lock, flags);
+}
+
+static void nop_submission_tasklet(unsigned long data)
+{
+}
+
+static void ring_reset_cancel(struct intel_engine_cs *engine)
+{
+	struct intel_engine_execlists * const el = &engine->execlists;
+	struct i915_request *rq, *rn;
+	unsigned long flags;
+	struct rb_node *rb;
+
+	cancel_port_requests(engine);
+
+	spin_lock_irqsave(&engine->active.lock, flags);
+
+	__ring_rewind(engine, true);
+
+	/* Mark all submitted requests as skipped. */
+	list_for_each_entry(rq, &engine->active.requests, sched.link) {
+		i915_request_set_error_once(rq, -EIO);
+		i915_request_mark_complete(rq);
+	}
+
+	/* Flush the queued requests to the timeline list (for retiring). */
+	while ((rb = rb_first_cached(&el->queue))) {
+		struct i915_priolist *p = to_priolist(rb);
+
+		priolist_for_each_request_consume(rq, rn, p) {
+			i915_request_set_error_once(rq, -EIO);
+			i915_request_mark_complete(rq);
+			__i915_request_submit(rq);
+		}
+
+		rb_erase_cached(&p->node, &el->queue);
+		i915_priolist_free(p);
+	}
+	GEM_BUG_ON(!RB_EMPTY_ROOT(&el->queue.rb_root));
+
+	/* Remaining _unready_ requests will be nop'ed when submitted */
+
+	GEM_BUG_ON(__tasklet_is_enabled(&el->tasklet));
+	el->tasklet.func = nop_submission_tasklet;
+
+	spin_unlock_irqrestore(&engine->active.lock, flags);
+}
+
+static void reset_finish(struct intel_engine_cs *engine)
+{
+	intel_ring_submission_reset_finish(engine);
+
+	if (__tasklet_enable(&engine->execlists.tasklet))
+		tasklet_hi_schedule(&engine->execlists.tasklet);
+}
+
+static void submission_park(struct intel_engine_cs *engine)
+{
+	intel_engine_unpin_breadcrumbs_irq(engine);
+	/* drain the submit queue */
+	tasklet_hi_schedule(&engine->execlists.tasklet);
+}
+
+static void submission_unpark(struct intel_engine_cs *engine)
+{
+	intel_engine_pin_breadcrumbs_irq(engine);
+}
+
+static void ring_context_destroy(struct kref *ref)
+{
+	struct intel_context *ce = container_of(ref, typeof(*ce), ref);
+
+	GEM_BUG_ON(intel_context_is_pinned(ce));
+
+	if (ce->state)
+		i915_vma_put(ce->state);
+	if (test_bit(CONTEXT_ALLOC_BIT, &ce->flags))
+		intel_ring_put(ce->ring);
+
+	intel_context_fini(ce);
+	intel_context_free(ce);
+}
+
+static void ring_context_unpin(struct intel_context *ce)
+{
+}
+
+static int alloc_context_vma(struct intel_context *ce)
+
+{
+	struct intel_engine_cs *engine = ce->engine;
+	struct drm_i915_gem_object *obj;
+	struct i915_vma *vma;
+	int err;
+
+	obj = i915_gem_object_create_shmem(engine->i915, engine->context_size);
+	if (IS_ERR(obj))
+		return PTR_ERR(obj);
+
+	/*
+	 * Try to make the context utilize L3 as well as LLC.
+	 *
+	 * On VLV we don't have L3 controls in the PTEs so we
+	 * shouldn't touch the cache level, especially as that
+	 * would make the object snooped which might have a
+	 * negative performance impact.
+	 *
+	 * Snooping is required on non-llc platforms in execlist
+	 * mode, but since all GGTT accesses use PAT entry 0 we
+	 * get snooping anyway regardless of cache_level.
+	 *
+	 * This is only applicable for Ivy Bridge devices since
+	 * later platforms don't have L3 control bits in the PTE.
+	 */
+	if (IS_IVYBRIDGE(engine->i915))
+		i915_gem_object_set_cache_coherency(obj, I915_CACHE_L3_LLC);
+
+	if (engine->default_state) {
+		void *vaddr;
+
+		vaddr = i915_gem_object_pin_map(obj, I915_MAP_WB);
+		if (IS_ERR(vaddr)) {
+			err = PTR_ERR(vaddr);
+			goto err_obj;
+		}
+
+		shmem_read(engine->default_state, 0,
+			   vaddr, engine->context_size);
+		__set_bit(CONTEXT_VALID_BIT, &ce->flags);
+
+		i915_gem_object_flush_map(obj);
+		i915_gem_object_unpin_map(obj);
+	}
+
+	vma = i915_vma_instance(obj, &engine->gt->ggtt->vm, NULL);
+	if (IS_ERR(vma)) {
+		err = PTR_ERR(vma);
+		goto err_obj;
+	}
+
+	ce->state = vma;
+	return 0;
+
+err_obj:
+	i915_gem_object_put(obj);
+	return err;
+}
+
+static int alloc_timeline(struct intel_context *ce)
+{
+	struct intel_engine_cs *engine = ce->engine;
+	struct intel_timeline *tl;
+	struct i915_vma *hwsp;
+
+	/*
+	 * Use the static global HWSP for the kernel context, and
+	 * a dynamically allocated cacheline for everyone else.
+	 */
+	hwsp = NULL;
+	if (unlikely(intel_context_is_barrier(ce)))
+		hwsp = engine->status_page.vma;
+
+	tl = intel_timeline_create(engine->gt, hwsp);
+	if (IS_ERR(tl))
+		return PTR_ERR(tl);
+
+	ce->timeline = tl;
+	return 0;
+}
+
+static int ring_context_alloc(struct intel_context *ce)
+{
+	struct intel_engine_cs *engine = ce->engine;
+	struct intel_ring *ring;
+	int err;
+
+	GEM_BUG_ON(ce->state);
+	if (engine->context_size) {
+		err = alloc_context_vma(ce);
+		if (err)
+			return err;
+	}
+
+	if (!ce->timeline) {
+		err = alloc_timeline(ce);
+		if (err)
+			goto err_vma;
+	}
+
+	ring = intel_engine_create_ring(engine,
+					(unsigned long)ce->ring |
+					INTEL_RING_CREATE_INTERNAL);
+	if (IS_ERR(ring)) {
+		err = PTR_ERR(ring);
+		goto err_timeline;
+	}
+	ce->ring = ring;
+
+	return 0;
+
+err_timeline:
+	intel_timeline_put(ce->timeline);
+err_vma:
+	if (ce->state) {
+		i915_vma_put(ce->state);
+		ce->state = NULL;
+	}
+	return err;
+}
+
+static int ring_context_pin(struct intel_context *ce)
+{
+	return 0;
+}
+
+static void ring_context_reset(struct intel_context *ce)
+{
+	intel_ring_reset(ce->ring, 0);
+	clear_bit(CONTEXT_VALID_BIT, &ce->flags);
+}
+
+static const struct intel_context_ops ring_context_ops = {
+	.alloc = ring_context_alloc,
+
+	.pin = ring_context_pin,
+	.unpin = ring_context_unpin,
+
+	.enter = intel_context_enter_engine,
+	.exit = intel_context_exit_engine,
+
+	.reset = ring_context_reset,
+	.destroy = ring_context_destroy,
+};
+
+static int ring_request_alloc(struct i915_request *rq)
+{
+	int ret;
+
+	GEM_BUG_ON(!intel_context_is_pinned(rq->context));
+
+	/*
+	 * Flush enough space to reduce the likelihood of waiting after
+	 * we start building the request - in which case we will just
+	 * have to repeat work.
+	 */
+	rq->reserved_space += LEGACY_REQUEST_SIZE;
+
+	/* Unconditionally invalidate GPU caches and TLBs. */
+	ret = rq->engine->emit_flush(rq, EMIT_INVALIDATE);
+	if (ret)
+		return ret;
+
+	rq->reserved_space -= LEGACY_REQUEST_SIZE;
+	return 0;
+}
+
+static void set_default_submission(struct intel_engine_cs *engine)
+{
+	engine->submit_request = submit_request;
+	engine->execlists.tasklet.func = submission_tasklet;
+}
+
+static void ring_release_global_submission(struct intel_engine_cs *engine)
+{
+	intel_ring_unpin(engine->legacy.ring);
+	intel_ring_put(engine->legacy.ring);
+}
+
+static void ring_release(struct intel_engine_cs *engine)
+{
+	intel_engine_cleanup_common(engine);
+
+	set_current_context(&engine->legacy.context, NULL);
+
+	ring_release_global_submission(engine);
+}
+
+static void setup_irq(struct intel_engine_cs *engine)
+{
+}
+
+static void setup_common(struct intel_engine_cs *engine)
+{
+	struct drm_i915_private *i915 = engine->i915;
+
+	/* gen8+ are only supported with execlists */
+	GEM_BUG_ON(INTEL_GEN(i915) >= 8);
+	GEM_BUG_ON(INTEL_GEN(i915) < 8);
+
+	setup_irq(engine);
+
+	engine->park = submission_park;
+	engine->unpark = submission_unpark;
+
+	engine->resume = intel_ring_submission_resume;
+	engine->reset.prepare = reset_prepare;
+	engine->reset.rewind = ring_reset_rewind;
+	engine->reset.cancel = ring_reset_cancel;
+	engine->reset.finish = reset_finish;
+
+	engine->cops = &ring_context_ops;
+	engine->request_alloc = ring_request_alloc;
+
+	engine->set_default_submission = set_default_submission;
+}
+
+static void setup_rcs(struct intel_engine_cs *engine)
+{
+}
+
+static void setup_vcs(struct intel_engine_cs *engine)
+{
+}
+
+static void setup_bcs(struct intel_engine_cs *engine)
+{
+}
+
+static void setup_vecs(struct intel_engine_cs *engine)
+{
+	GEM_BUG_ON(!IS_HASWELL(engine->i915));
+}
+
+static unsigned int global_ring_size(void)
+{
+	/* Enough space to hold 2 clients and the context switch */
+	return roundup_pow_of_two(EXECLIST_MAX_PORTS * SZ_16K + SZ_4K);
+}
+
+static int ring_setup_global_submission(struct intel_engine_cs *engine)
+{
+	struct i915_acquire_ctx acquire;
+	struct intel_ring *ring;
+	int err;
+
+	ring = intel_engine_create_ring(engine, global_ring_size());
+	if (IS_ERR(ring))
+		return PTR_ERR(ring);
+
+	i915_acquire_ctx_init(&acquire);
+
+	err = intel_ring_acquire_lock(ring, &acquire);
+	if (err)
+		goto err_acquire;
+
+	err = i915_acquire_mm(&acquire);
+	if (err)
+		goto err_acquire;
+
+	err = intel_ring_pin_locked(ring);
+	if (err)
+		goto err_acquire;
+
+	i915_acquire_ctx_fini(&acquire);
+
+	GEM_BUG_ON(engine->legacy.ring);
+	engine->legacy.ring = ring;
+	return 0;
+
+err_acquire:
+	i915_acquire_ctx_fini(&acquire);
+	intel_ring_put(ring);
+	return err;
+}
+
+int intel_ring_scheduler_setup(struct intel_engine_cs *engine)
+{
+	int err;
+
+	GEM_BUG_ON(HAS_EXECLISTS(engine->i915));
+
+	tasklet_init(&engine->execlists.tasklet,
+		     submission_tasklet, (unsigned long)engine);
+
+	setup_common(engine);
+
+	switch (engine->class) {
+	case RENDER_CLASS:
+		setup_rcs(engine);
+		break;
+	case VIDEO_DECODE_CLASS:
+		setup_vcs(engine);
+		break;
+	case COPY_ENGINE_CLASS:
+		setup_bcs(engine);
+		break;
+	case VIDEO_ENHANCEMENT_CLASS:
+		setup_vecs(engine);
+		break;
+	default:
+		MISSING_CASE(engine->class);
+		return -ENODEV;
+	}
+
+	err = ring_setup_global_submission(engine);
+	if (err)
+		goto err_common;
+
+	engine->flags |= I915_ENGINE_HAS_SCHEDULER;
+	engine->flags |= I915_ENGINE_NEEDS_BREADCRUMB_TASKLET;
+	engine->flags |= I915_ENGINE_SUPPORTS_STATS;
+
+	/* Finally, take ownership and responsibility for cleanup! */
+	engine->release = ring_release;
+	return 0;
+
+err_common:
+	intel_engine_cleanup_common(engine);
+	return err;
+}
diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
index ec54ff029699..4c3b75fbc899 100644
--- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
@@ -38,6 +38,7 @@
 #include "intel_gt.h"
 #include "intel_reset.h"
 #include "intel_ring.h"
+#include "intel_ring_submission.h"
 #include "shmem_utils.h"
 
 /* Rough estimate of the typical request size, performing a flush,
@@ -218,7 +219,7 @@ static void set_pp_dir(struct intel_engine_cs *engine)
 	}
 }
 
-static int xcs_resume(struct intel_engine_cs *engine)
+int intel_ring_submission_resume(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
 	struct intel_ring *ring = engine->legacy.ring;
@@ -322,7 +323,7 @@ static int xcs_resume(struct intel_engine_cs *engine)
 	return ret;
 }
 
-static void reset_prepare(struct intel_engine_cs *engine)
+void intel_ring_submission_reset_prepare(struct intel_engine_cs *engine)
 {
 	struct intel_uncore *uncore = engine->uncore;
 	const u32 base = engine->mmio_base;
@@ -429,7 +430,7 @@ static void reset_rewind(struct intel_engine_cs *engine, bool stalled)
 	spin_unlock_irqrestore(&engine->active.lock, flags);
 }
 
-static void reset_finish(struct intel_engine_cs *engine)
+void intel_ring_submission_reset_finish(struct intel_engine_cs *engine)
 {
 }
 
@@ -1065,11 +1066,11 @@ static void setup_common(struct intel_engine_cs *engine)
 
 	setup_irq(engine);
 
-	engine->resume = xcs_resume;
-	engine->reset.prepare = reset_prepare;
+	engine->resume = intel_ring_submission_resume;
+	engine->reset.prepare = intel_ring_submission_reset_prepare;
 	engine->reset.rewind = reset_rewind;
 	engine->reset.cancel = reset_cancel;
-	engine->reset.finish = reset_finish;
+	engine->reset.finish = intel_ring_submission_reset_finish;
 
 	engine->cops = &ring_context_ops;
 	engine->request_alloc = ring_request_alloc;
diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.h b/drivers/gpu/drm/i915/gt/intel_ring_submission.h
new file mode 100644
index 000000000000..701eb033e055
--- /dev/null
+++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2020 Intel Corporation
+ */
+
+#ifndef __INTEL_RING_SUBMISSION_H__
+#define __INTEL_RING_SUBMISSION_H__
+
+struct intel_engine_cs;
+
+void intel_ring_submission_reset_prepare(struct intel_engine_cs *engine);
+void intel_ring_submission_reset_finish(struct intel_engine_cs *engine);
+
+int intel_ring_submission_resume(struct intel_engine_cs *engine);
+
+#endif /* __INTEL_RING_SUBMISSION_H__ */
-- 
2.20.1

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