drm/i915: intel_ring_initialized() must be simple and inline

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@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@chris-wilson.co.uk>
Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1449586956-32360-2-git-send-email-david.s.gordon@intel.com

1 files changed, 12 insertions, 5 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;
 }