[PATCH 1/2] drm/i915: Introduce execlist_port_* accessors

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

From: Mika Kuoppala <mika.kuoppala@intel.com>

Instead of trusting that first available port is at index 0,
use accessor to hide this. This is a preparation for a
following patches where head can be at arbitrary location
in the port array.

v2: improved commit message, elsp_ready readability (Chris)
v3: s/execlist_port_index/execlist_port (Chris)
v4: rebase to new naming
v5: fix port_next indexing
v6: adapt to preempt

Cc: Michał Winiarski <michal.winiarski@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_gpu_error.c      |  6 ++--
 drivers/gpu/drm/i915/i915_guc_submission.c | 50 ++++++++++++++++++------------
 drivers/gpu/drm/i915/intel_engine_cs.c     | 18 ++++++-----
 drivers/gpu/drm/i915/intel_lrc.c           | 49 ++++++++++++++++++-----------
 drivers/gpu/drm/i915/intel_ringbuffer.h    | 44 ++++++++++++++++++++++++--
 5 files changed, 119 insertions(+), 48 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 653fb69e7ecb..6d0bdb03b3f0 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1333,11 +1333,13 @@ static void engine_record_requests(struct intel_engine_cs *engine,
 static void error_record_engine_execlists(struct intel_engine_cs *engine,
 					  struct drm_i915_error_engine *ee)
 {
-	const struct intel_engine_execlists * const execlists = &engine->execlists;
+	struct intel_engine_execlists * const execlists = &engine->execlists;
 	unsigned int n;
 
 	for (n = 0; n < execlists_num_ports(execlists); n++) {
-		struct drm_i915_gem_request *rq = port_request(&execlists->port[n]);
+		struct drm_i915_gem_request *rq;
+
+		rq = port_request(execlists_port(execlists, n));
 
 		if (!rq)
 			break;
diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index 3049a0781b88..4600d0878c96 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -678,16 +678,18 @@ static void i915_guc_submit(struct intel_engine_cs *engine)
 {
 	struct intel_guc *guc = &engine->i915->guc;
 	struct intel_engine_execlists * const execlists = &engine->execlists;
-	struct execlist_port *port = execlists->port;
 	unsigned int n;
 
 	for (n = 0; n < execlists_num_ports(execlists); n++) {
+		struct execlist_port *port;
 		struct drm_i915_gem_request *rq;
 		unsigned int count;
 
-		rq = port_unpack(&port[n], &count);
+		port = execlists_port(execlists, n);
+		rq = port_unpack(port, &count);
+
 		if (rq && count == 0) {
-			port_set(&port[n], port_pack(rq, ++count));
+			port_set(port, port_pack(rq, ++count));
 
 			flush_ggtt_writes(rq->ring->vma);
 
@@ -710,10 +712,8 @@ static void port_assign(struct execlist_port *port,
 static void i915_guc_dequeue(struct intel_engine_cs *engine)
 {
 	struct intel_engine_execlists * const execlists = &engine->execlists;
-	struct execlist_port *port = execlists->port;
+	struct execlist_port *port, *last_port;
 	struct drm_i915_gem_request *last = NULL;
-	const struct execlist_port * const last_port =
-		&execlists->port[execlists->port_mask];
 	bool submit = false;
 	struct rb_node *rb;
 
@@ -724,6 +724,9 @@ static void i915_guc_dequeue(struct intel_engine_cs *engine)
 	if (!rb)
 		goto unlock;
 
+	port = execlists_port_head(execlists);
+	last_port = execlists_port_tail(execlists);
+
 	if (HAS_LOGICAL_RING_PREEMPTION(engine->i915) && port_isset(port)) {
 		struct guc_preempt_work *preempt_work =
 			&engine->i915->guc.preempt_work[engine->id];
@@ -739,7 +742,7 @@ static void i915_guc_dequeue(struct intel_engine_cs *engine)
 			goto unlock;
 		}
 
-		port++;
+		port = execlists_port_next(execlists, port);
 	}
 
 	do {
@@ -756,7 +759,8 @@ static void i915_guc_dequeue(struct intel_engine_cs *engine)
 
 				if (submit)
 					port_assign(port, last);
-				port++;
+
+				port = execlists_port_next(execlists, port);
 			}
 
 			INIT_LIST_HEAD(&rq->priotree.link);
@@ -784,24 +788,32 @@ static void i915_guc_dequeue(struct intel_engine_cs *engine)
 	spin_unlock_irq(&engine->timeline->lock);
 }
 
-static void i915_guc_irq_handler(unsigned long data)
+static void guc_complete_ready_ports(struct intel_engine_execlists * const execlists)
 {
-	struct intel_engine_cs * const engine = (struct intel_engine_cs *)data;
-	struct intel_engine_execlists * const execlists = &engine->execlists;
-	struct execlist_port *port = execlists->port;
-	struct drm_i915_gem_request *rq;
+	struct execlist_port *port = execlists_port_head(execlists);
+
+	while (port_isset(port)) {
+		struct drm_i915_gem_request *rq = port_request(port);
+
+		if (!i915_gem_request_completed(rq))
+			break;
 
-	rq = port_request(&port[0]);
-	while (rq && i915_gem_request_completed(rq)) {
 		trace_i915_gem_request_out(rq);
 		i915_gem_request_put(rq);
 
-		execlists_port_complete(execlists, port);
+		port = execlists_head_complete(execlists, port);
+	};
 
-		rq = port_request(&port[0]);
-	}
-	if (!rq)
+	if (!port_isset(port))
 		execlists_clear_active(execlists, EXECLISTS_ACTIVE_USER);
+}
+
+static void i915_guc_irq_handler(unsigned long data)
+{
+	struct intel_engine_cs * const engine = (struct intel_engine_cs *)data;
+	struct intel_engine_execlists * const execlists = &engine->execlists;
+
+	guc_complete_ready_ports(execlists);
 
 	if (execlists_is_active(execlists, EXECLISTS_ACTIVE_PREEMPT) &&
 	    intel_read_status_page(engine, I915_GEM_HWS_PREEMPT_INDEX) ==
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index f31f2d6384c3..1c08185a05ed 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -1673,7 +1673,7 @@ static void print_request(struct drm_printer *m,
 void intel_engine_dump(struct intel_engine_cs *engine, struct drm_printer *m)
 {
 	struct intel_breadcrumbs * const b = &engine->breadcrumbs;
-	const struct intel_engine_execlists * const execlists = &engine->execlists;
+	struct intel_engine_execlists * const execlists = &engine->execlists;
 	struct i915_gpu_error * const error = &engine->i915->gpu_error;
 	struct drm_i915_private *dev_priv = engine->i915;
 	struct drm_i915_gem_request *rq;
@@ -1777,16 +1777,20 @@ void intel_engine_dump(struct intel_engine_cs *engine, struct drm_printer *m)
 
 		rcu_read_lock();
 		for (idx = 0; idx < execlists_num_ports(execlists); idx++) {
-			unsigned int count;
+			struct execlist_port *port;
+			unsigned int count, idx_abs;
+
+			port = execlists_port(execlists, idx);
+			idx_abs = port_index(port, execlists);
 
-			rq = port_unpack(&execlists->port[idx], &count);
+			rq = port_unpack(port, &count);
 			if (rq) {
-				drm_printf(m, "\t\tELSP[%d] count=%d, ",
-					   idx, count);
+				drm_printf(m, "\t\tELSP[%d:%d] count=%d, ",
+					   idx, idx_abs, count);
 				print_request(m, rq, "rq: ");
 			} else {
-				drm_printf(m, "\t\tELSP[%d] idle\n",
-					   idx);
+				drm_printf(m, "\t\tELSP[%d:%d] idle\n",
+					   idx, idx_abs);
 			}
 		}
 		drm_printf(m, "\t\tHW active? 0x%x\n", execlists->active);
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 6840ec8db037..62c3e06a110d 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -448,24 +448,26 @@ static inline void elsp_write(u64 desc, u32 __iomem *elsp)
 
 static void execlists_submit_ports(struct intel_engine_cs *engine)
 {
-	struct execlist_port *port = engine->execlists.port;
+	struct intel_engine_execlists * const execlists = &engine->execlists;
 	u32 __iomem *elsp =
 		engine->i915->regs + i915_mmio_reg_offset(RING_ELSP(engine));
 	unsigned int n;
 
-	for (n = execlists_num_ports(&engine->execlists); n--; ) {
+	for (n = execlists_num_ports(execlists); n--; ) {
+		struct execlist_port *port;
 		struct drm_i915_gem_request *rq;
 		unsigned int count;
 		u64 desc;
 
-		rq = port_unpack(&port[n], &count);
+		port = execlists_port(execlists, n);
+		rq = port_unpack(port, &count);
 		if (rq) {
 			GEM_BUG_ON(count > !n);
 			if (!count++)
 				execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_IN);
-			port_set(&port[n], port_pack(rq, count));
+			port_set(port, port_pack(rq, count));
 			desc = execlists_update_context(rq);
-			GEM_DEBUG_EXEC(port[n].context_id = upper_32_bits(desc));
+			GEM_DEBUG_EXEC(port->context_id = upper_32_bits(desc));
 		} else {
 			GEM_BUG_ON(!n);
 			desc = 0;
@@ -529,10 +531,8 @@ static void inject_preempt_context(struct intel_engine_cs *engine)
 static void execlists_dequeue(struct intel_engine_cs *engine)
 {
 	struct intel_engine_execlists * const execlists = &engine->execlists;
-	struct execlist_port *port = execlists->port;
-	const struct execlist_port * const last_port =
-		&execlists->port[execlists->port_mask];
-	struct drm_i915_gem_request *last = port_request(port);
+	struct execlist_port *port, *last_port;
+	struct drm_i915_gem_request *last;
 	struct rb_node *rb;
 	bool submit = false;
 
@@ -563,6 +563,9 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 	if (!rb)
 		goto unlock;
 
+	port = execlists_port_head(execlists);
+	last = port_request(port);
+
 	if (last) {
 		/*
 		 * Don't resubmit or switch until all outstanding
@@ -570,7 +573,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 		 * know the next preemption status we see corresponds
 		 * to this ELSP update.
 		 */
-		if (port_count(&port[0]) > 1)
+		if (port_count(port) > 1)
 			goto unlock;
 
 		if (HAS_LOGICAL_RING_PREEMPTION(engine->i915) &&
@@ -605,7 +608,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 			 * the driver is unable to keep up the supply of new
 			 * work).
 			 */
-			if (port_count(&port[1]))
+			if (port_count(execlists_port_next(execlists, port)))
 				goto unlock;
 
 			/* WaIdleLiteRestore:bdw,skl
@@ -619,6 +622,8 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 		}
 	}
 
+	last_port = execlists_port_tail(execlists);
+
 	do {
 		struct i915_priolist *p = rb_entry(rb, typeof(*p), node);
 		struct drm_i915_gem_request *rq, *rn;
@@ -665,7 +670,8 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 
 				if (submit)
 					port_assign(port, last);
-				port++;
+
+				port = execlists_port_next(execlists, port);
 
 				GEM_BUG_ON(port_isset(port));
 			}
@@ -699,8 +705,10 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 void
 execlists_cancel_port_requests(struct intel_engine_execlists * const execlists)
 {
-	struct execlist_port *port = execlists->port;
 	unsigned int num_ports = execlists_num_ports(execlists);
+	struct execlist_port *port;
+
+	port = execlists_port_head(execlists);
 
 	while (num_ports-- && port_isset(port)) {
 		struct drm_i915_gem_request *rq = port_request(port);
@@ -709,9 +717,10 @@ execlists_cancel_port_requests(struct intel_engine_execlists * const execlists)
 		execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_PREEMPTED);
 		i915_gem_request_put(rq);
 
-		memset(port, 0, sizeof(*port));
-		port++;
+		port = execlists_head_complete(execlists, port);
 	}
+
+	GEM_BUG_ON(port_isset(execlists_port_head(execlists)));
 }
 
 static void execlists_cancel_requests(struct intel_engine_cs *engine)
@@ -778,7 +787,6 @@ static void intel_lrc_irq_handler(unsigned long data)
 {
 	struct intel_engine_cs * const engine = (struct intel_engine_cs *)data;
 	struct intel_engine_execlists * const execlists = &engine->execlists;
-	struct execlist_port * const port = execlists->port;
 	struct drm_i915_private *dev_priv = engine->i915;
 
 	/* We can skip acquiring intel_runtime_pm_get() here as it was taken
@@ -797,6 +805,8 @@ static void intel_lrc_irq_handler(unsigned long data)
 	 * new request (outside of the context-switch interrupt).
 	 */
 	while (test_bit(ENGINE_IRQ_EXECLIST, &engine->irq_posted)) {
+		struct execlist_port *port;
+
 		/* The HWSP contains a (cacheable) mirror of the CSB */
 		const u32 *buf =
 			&engine->status_page.page_addr[I915_HWS_CSB_BUF0_INDEX];
@@ -833,6 +843,8 @@ static void intel_lrc_irq_handler(unsigned long data)
 			tail = READ_ONCE(buf[write_idx]);
 		}
 
+		port = execlists_port_head(execlists);
+
 		while (head != tail) {
 			struct drm_i915_gem_request *rq;
 			unsigned int status;
@@ -895,7 +907,7 @@ static void intel_lrc_irq_handler(unsigned long data)
 				trace_i915_gem_request_out(rq);
 				i915_gem_request_put(rq);
 
-				execlists_port_complete(execlists, port);
+				port = execlists_head_complete(execlists, port);
 			} else {
 				port_set(port, port_pack(rq, count));
 			}
@@ -935,6 +947,7 @@ static void insert_request(struct intel_engine_cs *engine,
 static void execlists_submit_request(struct drm_i915_gem_request *request)
 {
 	struct intel_engine_cs *engine = request->engine;
+	struct intel_engine_execlists * const execlists = &engine->execlists;
 	unsigned long flags;
 
 	/* Will be called from irq-context when using foreign fences. */
@@ -942,7 +955,7 @@ static void execlists_submit_request(struct drm_i915_gem_request *request)
 
 	insert_request(engine, &request->priotree, request->priotree.priority);
 
-	GEM_BUG_ON(!engine->execlists.first);
+	GEM_BUG_ON(!execlists->first);
 	GEM_BUG_ON(list_empty(&request->priotree.link));
 
 	spin_unlock_irqrestore(&engine->timeline->lock, flags);
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 69ad875fd011..387667fe50d3 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -259,6 +259,11 @@ struct intel_engine_execlists {
 	unsigned int port_mask;
 
 	/**
+	 * @port_head: first used execlist port
+	 */
+	unsigned int port_head;
+
+	/**
 	 * @queue: queue of requests, in priority lists
 	 */
 	struct rb_root queue;
@@ -569,8 +574,41 @@ execlists_num_ports(const struct intel_engine_execlists * const execlists)
 	return execlists->port_mask + 1;
 }
 
-static inline void
-execlists_port_complete(struct intel_engine_execlists * const execlists,
+#define __port_add(start, n, mask) (((start) + (n)) & (mask))
+#define port_head_add(e, n) __port_add((e)->port_head, n, (e)->port_mask)
+
+/* Index starting from port_head */
+static inline struct execlist_port *
+execlists_port(struct intel_engine_execlists * const execlists,
+	       const unsigned int n)
+{
+	return &execlists->port[port_head_add(execlists, n)];
+}
+
+static inline struct execlist_port *
+execlists_port_head(struct intel_engine_execlists * const execlists)
+{
+	return execlists_port(execlists, 0);
+}
+
+static inline struct execlist_port *
+execlists_port_tail(struct intel_engine_execlists * const execlists)
+{
+	return execlists_port(execlists, -1);
+}
+
+static inline struct execlist_port *
+execlists_port_next(struct intel_engine_execlists * const execlists,
+		    const struct execlist_port * const port)
+{
+	const unsigned int n = __port_add(port_index(port, execlists),
+					  1,
+					  execlists->port_mask);
+	return &execlists->port[n];
+}
+
+static inline struct execlist_port *
+execlists_head_complete(struct intel_engine_execlists * const execlists,
 			struct execlist_port * const port)
 {
 	const unsigned int m = execlists->port_mask;
@@ -580,6 +618,8 @@ execlists_port_complete(struct intel_engine_execlists * const execlists,
 
 	memmove(port, port + 1, m * sizeof(struct execlist_port));
 	memset(port + m, 0, sizeof(struct execlist_port));
+
+	return execlists_port_head(execlists);
 }
 
 static inline unsigned int
-- 
2.11.0

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