[Intel-gfx] [PATCH 1/1] drm/i915: intel_ring_initialized() must be simple and inline

[Dave Gordon]

Based on Chris Wilson's patch from 6 months ago, rebased and adapted.

The current implementation of intel_ring_initialized() is too heavyweight;
it's a non-inlined function that chases several levels of pointers. This
wouldn't matter too much if it were rarely called, but it's used inside
the iterator test of for_each_ring() and is therefore called quite
frequently. So let's make it simple and inline ...

The idea here is to use ring->dev as an indicator showing which engines
have been initialised and are therefore to be included in iterations that
use for_each_ring(). This allows us to avoid multiple memory references
and a (non-inlined) function call on each iteration of each such loop.

	Fixes regression from
	commit 48d823878d64f93163f5a949623346748bbce1b4
	Author: Oscar Mateo <oscar.mateo at intel.com>
	Date:   Thu Jul 24 17:04:23 2014 +0100

	    drm/i915/bdw: Generic logical ring init and cleanup

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Dave Gordon <david.s.gordon at intel.com>
---
 drivers/gpu/drm/i915/intel_lrc.c        | 17 +++++++++-----
 drivers/gpu/drm/i915/intel_ringbuffer.c | 39 +++++++++++----------------------
 drivers/gpu/drm/i915/intel_ringbuffer.h |  6 ++++-
 3 files changed, 30 insertions(+), 32 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 4ebafab..7644c48 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1894,8 +1894,10 @@ void intel_logical_ring_cleanup(struct intel_engine_cs *ring)
 
 	dev_priv = ring->dev->dev_private;
 
-	intel_logical_ring_stop(ring);
-	WARN_ON((I915_READ_MODE(ring) & MODE_IDLE) == 0);
+	if (ring->buffer) {
+		intel_logical_ring_stop(ring);
+		WARN_ON((I915_READ_MODE(ring) & MODE_IDLE) == 0);
+	}
 
 	if (ring->cleanup)
 		ring->cleanup(ring);
@@ -1909,6 +1911,7 @@ void intel_logical_ring_cleanup(struct intel_engine_cs *ring)
 	}
 
 	lrc_destroy_wa_ctx_obj(ring);
+	ring->dev = NULL;
 }
 
 static int logical_ring_init(struct drm_device *dev, struct intel_engine_cs *ring)
@@ -1931,11 +1934,11 @@ static int logical_ring_init(struct drm_device *dev, struct intel_engine_cs *rin
 
 	ret = i915_cmd_parser_init_ring(ring);
 	if (ret)
-		return ret;
+		goto error;
 
 	ret = intel_lr_context_deferred_alloc(ring->default_context, ring);
 	if (ret)
-		return ret;
+		goto error;
 
 	/* As this is the default context, always pin it */
 	ret = intel_lr_context_do_pin(
@@ -1946,9 +1949,13 @@ static int logical_ring_init(struct drm_device *dev, struct intel_engine_cs *rin
 		DRM_ERROR(
 			"Failed to pin and map ringbuffer %s: %d\n",
 			ring->name, ret);
-		return ret;
+		goto error;
 	}
 
+	return 0;
+
+error:
+	intel_logical_ring_cleanup(ring);
 	return ret;
 }
 
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 57d78f2..921c8a6 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -33,23 +33,6 @@
 #include "i915_trace.h"
 #include "intel_drv.h"
 
-bool
-intel_ring_initialized(struct intel_engine_cs *ring)
-{
-	struct drm_device *dev = ring->dev;
-
-	if (!dev)
-		return false;
-
-	if (i915.enable_execlists) {
-		struct intel_context *dctx = ring->default_context;
-		struct intel_ringbuffer *ringbuf = dctx->engine[ring->id].ringbuf;
-
-		return ringbuf->obj;
-	} else
-		return ring->buffer && ring->buffer->obj;
-}
-
 int __intel_ring_space(int head, int tail, int size)
 {
 	int space = head - tail;
@@ -2167,8 +2150,10 @@ static int intel_init_ring_buffer(struct drm_device *dev,
 	init_waitqueue_head(&ring->irq_queue);
 
 	ringbuf = intel_engine_create_ringbuffer(ring, 32 * PAGE_SIZE);
-	if (IS_ERR(ringbuf))
-		return PTR_ERR(ringbuf);
+	if (IS_ERR(ringbuf)) {
+		ret = PTR_ERR(ringbuf);
+		goto error;
+	}
 	ring->buffer = ringbuf;
 
 	if (I915_NEED_GFX_HWS(dev)) {
@@ -2197,8 +2182,7 @@ static int intel_init_ring_buffer(struct drm_device *dev,
 	return 0;
 
 error:
-	intel_ringbuffer_free(ringbuf);
-	ring->buffer = NULL;
+	intel_cleanup_ring_buffer(ring);
 	return ret;
 }
 
@@ -2211,12 +2195,14 @@ void intel_cleanup_ring_buffer(struct intel_engine_cs *ring)
 
 	dev_priv = to_i915(ring->dev);
 
-	intel_stop_ring_buffer(ring);
-	WARN_ON(!IS_GEN2(ring->dev) && (I915_READ_MODE(ring) & MODE_IDLE) == 0);
+	if (ring->buffer) {
+		intel_stop_ring_buffer(ring);
+		WARN_ON(!IS_GEN2(ring->dev) && (I915_READ_MODE(ring) & MODE_IDLE) == 0);
 
-	intel_unpin_ringbuffer_obj(ring->buffer);
-	intel_ringbuffer_free(ring->buffer);
-	ring->buffer = NULL;
+		intel_unpin_ringbuffer_obj(ring->buffer);
+		intel_ringbuffer_free(ring->buffer);
+		ring->buffer = NULL;
+	}
 
 	if (ring->cleanup)
 		ring->cleanup(ring);
@@ -2225,6 +2211,7 @@ void intel_cleanup_ring_buffer(struct intel_engine_cs *ring)
 
 	i915_cmd_parser_fini_ring(ring);
 	i915_gem_batch_pool_fini(&ring->batch_pool);
+	ring->dev = NULL;
 }
 
 static int ring_wait_for_space(struct intel_engine_cs *ring, int n)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 5d1eb20..49574ff 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -350,7 +350,11 @@ struct  intel_engine_cs {
 	u32 (*get_cmd_length_mask)(u32 cmd_header);
 };
 
-bool intel_ring_initialized(struct intel_engine_cs *ring);
+static inline bool
+intel_ring_initialized(struct intel_engine_cs *ring)
+{
+	return ring->dev != NULL;
+}
 
 static inline unsigned
 intel_ring_flag(struct intel_engine_cs *ring)
-- 
1.9.1