drm/i915: Update a bunch of LRC functions to take requests

A bunch of the low level LRC functions were passing around ringbuf and ctx
pairs. In a few cases, they took the r/c pair and a request as well. This is all
quite messy and unnecesary. The context_queue() call is especially bad since the
fake request code got removed - it takes a request and three extra things that
must be extracted from the request and then it checks them against what it finds
in the request. Removing all the derivable data makes the code much simpler all
round.

This patch updates those functions to just take the request structure.

Note that logical_ring_wait_for_space now takes a request structure but already
had a local request pointer that it uses to scan for something to wait on. To
avoid confusion the local variable has been renamed 'target' (it is searching
for a target request to do something with) and the parameter has been called req
(to guarantee anything accidentally missed gets a compiler error).

v2: Updated commit message re wait_for_space (Tomas Elf review comment).

For: VIZ-5115
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Tomas Elf <tomas.elf@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_lrc.c

@@ -544,23 +544,18 @@ void intel_lrc_irq_handler(struct intel_engine_cs *ring)
 		   ((u32)ring->next_context_status_buffer & 0x07) << 8);
 }
 
-static int execlists_context_queue(struct intel_engine_cs *ring,
-				   struct intel_context *to,
-				   u32 tail,
-				   struct drm_i915_gem_request *request)
+static int execlists_context_queue(struct drm_i915_gem_request *request)
 {
+	struct intel_engine_cs *ring = request->ring;
 	struct drm_i915_gem_request *cursor;
 	int num_elements = 0;
 
-	if (to != ring->default_context)
-		intel_lr_context_pin(ring, to);
-
-	WARN_ON(!request);
-	WARN_ON(to != request->ctx);
+	if (request->ctx != ring->default_context)
+		intel_lr_context_pin(ring, request->ctx);
 
 	i915_gem_request_reference(request);
 
-	request->tail = tail;
+	request->tail = request->ringbuf->tail;
 
 	spin_lock_irq(&ring->execlist_lock);
 
@@ -575,7 +570,7 @@ static int execlists_context_queue(struct intel_engine_cs *ring,
 					   struct drm_i915_gem_request,
 					   execlist_link);
 
-		if (to == tail_req->ctx) {
+		if (request->ctx == tail_req->ctx) {
 			WARN(tail_req->elsp_submitted != 0,
 				"More than 2 already-submitted reqs queued\n");
 			list_del(&tail_req->execlist_link);
@@ -659,12 +654,12 @@ int intel_logical_ring_alloc_request_extras(struct drm_i915_gem_request *request
 	return 0;
 }
 
-static int logical_ring_wait_for_space(struct intel_ringbuffer *ringbuf,
-				       struct intel_context *ctx,
+static int logical_ring_wait_for_space(struct drm_i915_gem_request *req,
 				       int bytes)
 {
-	struct intel_engine_cs *ring = ringbuf->ring;
-	struct drm_i915_gem_request *request;
+	struct intel_ringbuffer *ringbuf = req->ringbuf;
+	struct intel_engine_cs *ring = req->ring;
+	struct drm_i915_gem_request *target;
 	unsigned space;
 	int ret;
 
@@ -674,26 +669,26 @@ static int logical_ring_wait_for_space(struct intel_ringbuffer *ringbuf,
 	if (intel_ring_space(ringbuf) >= bytes)
 		return 0;
 
-	list_for_each_entry(request, &ring->request_list, list) {
+	list_for_each_entry(target, &ring->request_list, list) {
 		/*
 		 * The request queue is per-engine, so can contain requests
 		 * from multiple ringbuffers. Here, we must ignore any that
 		 * aren't from the ringbuffer we're considering.
 		 */
-		if (request->ringbuf != ringbuf)
+		if (target->ringbuf != ringbuf)
 			continue;
 
 		/* Would completion of this request free enough space? */
-		space = __intel_ring_space(request->postfix, ringbuf->tail,
+		space = __intel_ring_space(target->postfix, ringbuf->tail,
 					   ringbuf->size);
 		if (space >= bytes)
 			break;
 	}
 
-	if (WARN_ON(&request->list == &ring->request_list))
+	if (WARN_ON(&target->list == &ring->request_list))
 		return -ENOSPC;
 
-	ret = i915_wait_request(request);
+	ret = i915_wait_request(target);
 	if (ret)
 		return ret;
 
@@ -703,39 +698,37 @@ static int logical_ring_wait_for_space(struct intel_ringbuffer *ringbuf,
 
 /*
  * intel_logical_ring_advance_and_submit() - advance the tail and submit the workload
- * @ringbuf: Logical Ringbuffer to advance.
+ * @request: Request to advance the logical ringbuffer of.
  *
  * The tail is updated in our logical ringbuffer struct, not in the actual context. What
  * really happens during submission is that the context and current tail will be placed
  * on a queue waiting for the ELSP to be ready to accept a new context submission. At that
  * point, the tail *inside* the context is updated and the ELSP written to.
  */
 static void
-intel_logical_ring_advance_and_submit(struct intel_ringbuffer *ringbuf,
-				      struct intel_context *ctx,
-				      struct drm_i915_gem_request *request)
+intel_logical_ring_advance_and_submit(struct drm_i915_gem_request *request)
 {
-	struct intel_engine_cs *ring = ringbuf->ring;
+	struct intel_engine_cs *ring = request->ring;
 
-	intel_logical_ring_advance(ringbuf);
+	intel_logical_ring_advance(request->ringbuf);
 
 	if (intel_ring_stopped(ring))
 		return;
 
-	execlists_context_queue(ring, ctx, ringbuf->tail, request);
+	execlists_context_queue(request);
 }
 
-static int logical_ring_wrap_buffer(struct intel_ringbuffer *ringbuf,
-				    struct intel_context *ctx)
+static int logical_ring_wrap_buffer(struct drm_i915_gem_request *req)
 {
+	struct intel_ringbuffer *ringbuf = req->ringbuf;
 	uint32_t __iomem *virt;
 	int rem = ringbuf->size - ringbuf->tail;
 
 	/* Can't wrap if space has already been reserved! */
 	WARN_ON(ringbuf->reserved_in_use);
 
 	if (ringbuf->space < rem) {
-		int ret = logical_ring_wait_for_space(ringbuf, ctx, rem);
+		int ret = logical_ring_wait_for_space(req, rem);
 
 		if (ret)
 			return ret;
@@ -752,9 +745,9 @@ static int logical_ring_wrap_buffer(struct intel_ringbuffer *ringbuf,
 	return 0;
 }
 
-static int logical_ring_prepare(struct intel_ringbuffer *ringbuf,
-				struct intel_context *ctx, int bytes)
+static int logical_ring_prepare(struct drm_i915_gem_request *req, int bytes)
 {
+	struct intel_ringbuffer *ringbuf = req->ringbuf;
 	int ret;
 
 	/*
@@ -766,7 +759,7 @@ static int logical_ring_prepare(struct intel_ringbuffer *ringbuf,
 		bytes += ringbuf->reserved_size;
 
 	if (unlikely(ringbuf->tail + bytes > ringbuf->effective_size)) {
-		ret = logical_ring_wrap_buffer(ringbuf, ctx);
+		ret = logical_ring_wrap_buffer(req);
 		if (unlikely(ret))
 			return ret;
 
@@ -779,7 +772,7 @@ static int logical_ring_prepare(struct intel_ringbuffer *ringbuf,
 	}
 
 	if (unlikely(ringbuf->space < bytes)) {
-		ret = logical_ring_wait_for_space(ringbuf, ctx, bytes);
+		ret = logical_ring_wait_for_space(req, bytes);
 		if (unlikely(ret))
 			return ret;
 	}
@@ -814,8 +807,7 @@ static int intel_logical_ring_begin(struct drm_i915_gem_request *req,
 	if (ret)
 		return ret;
 
-	ret = logical_ring_prepare(req->ringbuf, req->ctx,
-				   num_dwords * sizeof(uint32_t));
+	ret = logical_ring_prepare(req, num_dwords * sizeof(uint32_t));
 	if (ret)
 		return ret;
 
@@ -1557,7 +1549,7 @@ static int gen8_emit_request(struct drm_i915_gem_request *request)
 	intel_logical_ring_emit(ringbuf, i915_gem_request_get_seqno(request));
 	intel_logical_ring_emit(ringbuf, MI_USER_INTERRUPT);
 	intel_logical_ring_emit(ringbuf, MI_NOOP);
-	intel_logical_ring_advance_and_submit(ringbuf, request->ctx, request);
+	intel_logical_ring_advance_and_submit(request);
 
 	/*
 	 * Here we add two extra NOOPs as padding to avoid