drm/i915: intel_ring.engine is unused

Or rather it is used only by intel_ring_pin() to extract the
drm_i915_private which we can easily pass in. As this is a relatively
rare operation, save the space in the struct, and as such it is even
break even in the extra code for passing around the parameter:

add/remove: 0/0 grow/shrink: 2/3 up/down: 15/-15 (0)
function                                     old     new   delta
intel_init_ring_buffer                       906     918     +12
execlists_context_pin                       1308    1311      +3
mock_engine                                  407     403      -4
intel_engine_create_ring                     367     363      -4
intel_ring_pin                               326     319      -7
Total: Before=1261794, After=1261794, chg +0.00%

v2: Reorder intel_init_ring_buffer to keep the ring setup together:

add/remove: 0/0 grow/shrink: 2/3 up/down: 9/-15 (-6)
function                                     old     new   delta
intel_init_ring_buffer                       906     912      +6
execlists_context_pin                       1308    1311      +3
mock_engine                                  407     403      -4
intel_engine_create_ring                     367     363      -4
intel_ring_pin                               326     319      -7
Total: Before=1261794, After=1261788, chg -0.00%
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170403113426.25707-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_lrc.c

@@ -771,7 +771,7 @@ static int execlists_context_pin(struct intel_engine_cs *engine,
 		goto unpin_vma;
 	}
 
-	ret = intel_ring_pin(ce->ring, ctx->ggtt_offset_bias);
+	ret = intel_ring_pin(ce->ring, ctx->i915, ctx->ggtt_offset_bias);
 	if (ret)
 		goto unpin_map;
 

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -1270,17 +1270,18 @@ static int init_phys_status_page(struct intel_engine_cs *engine)
 	return 0;
 }
 
-int intel_ring_pin(struct intel_ring *ring, unsigned int offset_bias)
+int intel_ring_pin(struct intel_ring *ring,
+		   struct drm_i915_private *i915,
+		   unsigned int offset_bias)
 {
-	unsigned int flags;
-	enum i915_map_type map;
+	enum i915_map_type map = HAS_LLC(i915) ? I915_MAP_WB : I915_MAP_WC;
 	struct i915_vma *vma = ring->vma;
+	unsigned int flags;
 	void *addr;
 	int ret;
 
 	GEM_BUG_ON(ring->vaddr);
 
-	map = HAS_LLC(ring->engine->i915) ? I915_MAP_WB : I915_MAP_WC;
 
 	flags = PIN_GLOBAL;
 	if (offset_bias)
@@ -1369,8 +1370,6 @@ intel_engine_create_ring(struct intel_engine_cs *engine, int size)
 	if (!ring)
 		return ERR_PTR(-ENOMEM);
 
-	ring->engine = engine;
-
 	INIT_LIST_HEAD(&ring->request_list);
 
 	ring->size = size;
@@ -1481,7 +1480,6 @@ static void intel_ring_context_unpin(struct intel_engine_cs *engine,
 
 static int intel_init_ring_buffer(struct intel_engine_cs *engine)
 {
-	struct drm_i915_private *dev_priv = engine->i915;
 	struct intel_ring *ring;
 	int ret;
 
@@ -1493,13 +1491,7 @@ static int intel_init_ring_buffer(struct intel_engine_cs *engine)
 	if (ret)
 		goto error;
 
-	ring = intel_engine_create_ring(engine, 32 * PAGE_SIZE);
-	if (IS_ERR(ring)) {
-		ret = PTR_ERR(ring);
-		goto error;
-	}
-
-	if (HWS_NEEDS_PHYSICAL(dev_priv)) {
+	if (HWS_NEEDS_PHYSICAL(engine->i915)) {
 		WARN_ON(engine->id != RCS);
 		ret = init_phys_status_page(engine);
 		if (ret)
@@ -1510,8 +1502,14 @@ static int intel_init_ring_buffer(struct intel_engine_cs *engine)
 			goto error;
 	}
 
+	ring = intel_engine_create_ring(engine, 32 * PAGE_SIZE);
+	if (IS_ERR(ring)) {
+		ret = PTR_ERR(ring);
+		goto error;
+	}
+
 	/* Ring wraparound at offset 0 sometimes hangs. No idea why. */
-	ret = intel_ring_pin(ring, I915_GTT_PAGE_SIZE);
+	ret = intel_ring_pin(ring, engine->i915, I915_GTT_PAGE_SIZE);
 	if (ret) {
 		intel_ring_free(ring);
 		goto error;

drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -139,8 +139,6 @@ struct intel_ring {
 	struct i915_vma *vma;
 	void *vaddr;
 
-	struct intel_engine_cs *engine;
-
 	struct list_head request_list;
 
 	u32 head;
@@ -487,7 +485,9 @@ intel_write_status_page(struct intel_engine_cs *engine, int reg, u32 value)
 
 struct intel_ring *
 intel_engine_create_ring(struct intel_engine_cs *engine, int size);
-int intel_ring_pin(struct intel_ring *ring, unsigned int offset_bias);
+int intel_ring_pin(struct intel_ring *ring,
+		   struct drm_i915_private *i915,
+		   unsigned int offset_bias);
 void intel_ring_unpin(struct intel_ring *ring);
 void intel_ring_free(struct intel_ring *ring);
 

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

@@ -112,7 +112,6 @@ static struct intel_ring *mock_ring(struct intel_engine_cs *engine)
 	if (!ring)
 		return NULL;
 
-	ring->engine = engine;
 	ring->size = sz;
 	ring->effective_size = sz;
 	ring->vaddr = (void *)(ring + 1);