drm/i915: Implement GPU semaphores for inter-ring synchronisation on SNB

The bulk of the change is to convert the growing list of rings into an
array so that the relationship between the rings and the semaphore sync
registers can be easily computed.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 259 insertions, 156 deletions

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 21871b0766e..f71db0cf490 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -203,6 +203,7 @@ static int init_ring_common(struct intel_ring_buffer *ring)
 		if (ring->space < 0)
 			ring->space += ring->size;
 	}
+
 	return 0;
 }
 
@@ -281,17 +282,18 @@ cleanup_pipe_control(struct intel_ring_buffer *ring)
 static int init_render_ring(struct intel_ring_buffer *ring)
 {
 	struct drm_device *dev = ring->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	int ret = init_ring_common(ring);
 
 	if (INTEL_INFO(dev)->gen > 3) {
-		drm_i915_private_t *dev_priv = dev->dev_private;
 		int mode = VS_TIMER_DISPATCH << 16 | VS_TIMER_DISPATCH;
 		if (IS_GEN6(dev))
 			mode |= MI_FLUSH_ENABLE << 16 | MI_FLUSH_ENABLE;
 		I915_WRITE(MI_MODE, mode);
 	}
 
-	if (HAS_PIPE_CONTROL(dev)) {
+	if (INTEL_INFO(dev)->gen >= 6) {
+	} else if (HAS_PIPE_CONTROL(dev)) {
 		ret = init_pipe_control(ring);
 		if (ret)
 			return ret;
@@ -308,6 +310,80 @@ static void render_ring_cleanup(struct intel_ring_buffer *ring)
 	cleanup_pipe_control(ring);
 }
 
+static void
+update_semaphore(struct intel_ring_buffer *ring, int i, u32 seqno)
+{
+	struct drm_device *dev = ring->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	int id;
+
+	/*
+	 * cs -> 1 = vcs, 0 = bcs
+	 * vcs -> 1 = bcs, 0 = cs,
+	 * bcs -> 1 = cs, 0 = vcs.
+	 */
+	id = ring - dev_priv->ring;
+	id += 2 - i;
+	id %= 3;
+
+	intel_ring_emit(ring,
+			MI_SEMAPHORE_MBOX |
+			MI_SEMAPHORE_REGISTER |
+			MI_SEMAPHORE_UPDATE);
+	intel_ring_emit(ring, seqno);
+	intel_ring_emit(ring,
+			RING_SYNC_0(dev_priv->ring[id].mmio_base) + 4*i);
+}
+
+static int
+gen6_add_request(struct intel_ring_buffer *ring,
+		 u32 *result)
+{
+	u32 seqno;
+	int ret;
+
+	ret = intel_ring_begin(ring, 10);
+	if (ret)
+		return ret;
+
+	seqno = i915_gem_get_seqno(ring->dev);
+	update_semaphore(ring, 0, seqno);
+	update_semaphore(ring, 1, seqno);
+
+	intel_ring_emit(ring, MI_STORE_DWORD_INDEX);
+	intel_ring_emit(ring, I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
+	intel_ring_emit(ring, seqno);
+	intel_ring_emit(ring, MI_USER_INTERRUPT);
+	intel_ring_advance(ring);
+
+	*result = seqno;
+	return 0;
+}
+
+int
+intel_ring_sync(struct intel_ring_buffer *ring,
+		struct intel_ring_buffer *to,
+		u32 seqno)
+{
+	int ret;
+
+	ret = intel_ring_begin(ring, 4);
+	if (ret)
+		return ret;
+
+	intel_ring_emit(ring,
+			MI_SEMAPHORE_MBOX |
+			MI_SEMAPHORE_REGISTER |
+			intel_ring_sync_index(ring, to) << 17 |
+			MI_SEMAPHORE_COMPARE);
+	intel_ring_emit(ring, seqno);
+	intel_ring_emit(ring, 0);
+	intel_ring_emit(ring, MI_NOOP);
+	intel_ring_advance(ring);
+
+	return 0;
+}
+
 #define PIPE_CONTROL_FLUSH(ring__, addr__)					\
 do {									\
 	intel_ring_emit(ring__, GFX_OP_PIPE_CONTROL | PIPE_CONTROL_QW_WRITE |		\
@@ -317,131 +393,128 @@ do {									\
 	intel_ring_emit(ring__, 0);							\
 } while (0)
 
-/**
- * Creates a new sequence number, emitting a write of it to the status page
- * plus an interrupt, which will trigger i915_user_interrupt_handler.
- *
- * Must be called with struct_lock held.
- *
- * Returned sequence numbers are nonzero on success.
- */
 static int
-render_ring_add_request(struct intel_ring_buffer *ring,
-			u32 *result)
+pc_render_add_request(struct intel_ring_buffer *ring,
+		      u32 *result)
 {
 	struct drm_device *dev = ring->dev;
 	u32 seqno = i915_gem_get_seqno(dev);
 	struct pipe_control *pc = ring->private;
+	u32 scratch_addr = pc->gtt_offset + 128;
 	int ret;
 
-	if (IS_GEN6(dev)) {
-		ret = intel_ring_begin(ring, 6);
-		if (ret)
-		    return ret;
-
-		intel_ring_emit(ring, GFX_OP_PIPE_CONTROL | 3);
-		intel_ring_emit(ring, PIPE_CONTROL_QW_WRITE |
-				PIPE_CONTROL_WC_FLUSH | PIPE_CONTROL_IS_FLUSH |
-				PIPE_CONTROL_NOTIFY);
-		intel_ring_emit(ring, pc->gtt_offset | PIPE_CONTROL_GLOBAL_GTT);
-		intel_ring_emit(ring, seqno);
-		intel_ring_emit(ring, 0);
-		intel_ring_emit(ring, 0);
-	} else if (HAS_PIPE_CONTROL(dev)) {
-		u32 scratch_addr = pc->gtt_offset + 128;
+	/*
+	 * Workaround qword write incoherence by flushing the
+	 * PIPE_NOTIFY buffers out to memory before requesting
+	 * an interrupt.
+	 */
+	ret = intel_ring_begin(ring, 32);
+	if (ret)
+		return ret;
 
-		/*
-		 * Workaround qword write incoherence by flushing the
-		 * PIPE_NOTIFY buffers out to memory before requesting
-		 * an interrupt.
-		 */
-		ret = intel_ring_begin(ring, 32);
-		if (ret)
-			return ret;
+	intel_ring_emit(ring, GFX_OP_PIPE_CONTROL | PIPE_CONTROL_QW_WRITE |
+			PIPE_CONTROL_WC_FLUSH | PIPE_CONTROL_TC_FLUSH);
+	intel_ring_emit(ring, pc->gtt_offset | PIPE_CONTROL_GLOBAL_GTT);
+	intel_ring_emit(ring, seqno);
+	intel_ring_emit(ring, 0);
+	PIPE_CONTROL_FLUSH(ring, scratch_addr);
+	scratch_addr += 128; /* write to separate cachelines */
+	PIPE_CONTROL_FLUSH(ring, scratch_addr);
+	scratch_addr += 128;
+	PIPE_CONTROL_FLUSH(ring, scratch_addr);
+	scratch_addr += 128;
+	PIPE_CONTROL_FLUSH(ring, scratch_addr);
+	scratch_addr += 128;
+	PIPE_CONTROL_FLUSH(ring, scratch_addr);
+	scratch_addr += 128;
+	PIPE_CONTROL_FLUSH(ring, scratch_addr);
+	intel_ring_emit(ring, GFX_OP_PIPE_CONTROL | PIPE_CONTROL_QW_WRITE |
+			PIPE_CONTROL_WC_FLUSH | PIPE_CONTROL_TC_FLUSH |
+			PIPE_CONTROL_NOTIFY);
+	intel_ring_emit(ring, pc->gtt_offset | PIPE_CONTROL_GLOBAL_GTT);
+	intel_ring_emit(ring, seqno);
+	intel_ring_emit(ring, 0);
+	intel_ring_advance(ring);
 
-		intel_ring_emit(ring, GFX_OP_PIPE_CONTROL | PIPE_CONTROL_QW_WRITE |
-				PIPE_CONTROL_WC_FLUSH | PIPE_CONTROL_TC_FLUSH);
-		intel_ring_emit(ring, pc->gtt_offset | PIPE_CONTROL_GLOBAL_GTT);
-		intel_ring_emit(ring, seqno);
-		intel_ring_emit(ring, 0);
-		PIPE_CONTROL_FLUSH(ring, scratch_addr);
-		scratch_addr += 128; /* write to separate cachelines */
-		PIPE_CONTROL_FLUSH(ring, scratch_addr);
-		scratch_addr += 128;
-		PIPE_CONTROL_FLUSH(ring, scratch_addr);
-		scratch_addr += 128;
-		PIPE_CONTROL_FLUSH(ring, scratch_addr);
-		scratch_addr += 128;
-		PIPE_CONTROL_FLUSH(ring, scratch_addr);
-		scratch_addr += 128;
-		PIPE_CONTROL_FLUSH(ring, scratch_addr);
-		intel_ring_emit(ring, GFX_OP_PIPE_CONTROL | PIPE_CONTROL_QW_WRITE |
-				PIPE_CONTROL_WC_FLUSH | PIPE_CONTROL_TC_FLUSH |
-				PIPE_CONTROL_NOTIFY);
-		intel_ring_emit(ring, pc->gtt_offset | PIPE_CONTROL_GLOBAL_GTT);
-		intel_ring_emit(ring, seqno);
-		intel_ring_emit(ring, 0);
-	} else {
-		ret = intel_ring_begin(ring, 4);
-		if (ret)
-		    return ret;
+	*result = seqno;
+	return 0;
+}
 
-		intel_ring_emit(ring, MI_STORE_DWORD_INDEX);
-		intel_ring_emit(ring, I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
-		intel_ring_emit(ring, seqno);
+static int
+render_ring_add_request(struct intel_ring_buffer *ring,
+			u32 *result)
+{
+	struct drm_device *dev = ring->dev;
+	u32 seqno = i915_gem_get_seqno(dev);
+	int ret;
 
-		intel_ring_emit(ring, MI_USER_INTERRUPT);
-	}
+	ret = intel_ring_begin(ring, 4);
+	if (ret)
+		return ret;
 
+	intel_ring_emit(ring, MI_STORE_DWORD_INDEX);
+	intel_ring_emit(ring, I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
+	intel_ring_emit(ring, seqno);
+	intel_ring_emit(ring, MI_USER_INTERRUPT);
 	intel_ring_advance(ring);
+
 	*result = seqno;
 	return 0;
 }
 
 static u32
-render_ring_get_seqno(struct intel_ring_buffer *ring)
+ring_get_seqno(struct intel_ring_buffer *ring)
 {
-	struct drm_device *dev = ring->dev;
-	if (HAS_PIPE_CONTROL(dev)) {
-		struct pipe_control *pc = ring->private;
-		return pc->cpu_page[0];
-	} else
-		return intel_read_status_page(ring, I915_GEM_HWS_INDEX);
+	return intel_read_status_page(ring, I915_GEM_HWS_INDEX);
+}
+
+static u32
+pc_render_get_seqno(struct intel_ring_buffer *ring)
+{
+	struct pipe_control *pc = ring->private;
+	return pc->cpu_page[0];
 }
 
 static void
-render_ring_get_user_irq(struct intel_ring_buffer *ring)
+render_ring_get_irq(struct intel_ring_buffer *ring)
 {
 	struct drm_device *dev = ring->dev;
-	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
-	unsigned long irqflags;
 
-	spin_lock_irqsave(&dev_priv->user_irq_lock, irqflags);
-	if (dev->irq_enabled && (++ring->user_irq_refcount == 1)) {
+	if (dev->irq_enabled && ++ring->irq_refcount == 1) {
+		drm_i915_private_t *dev_priv = dev->dev_private;
+		unsigned long irqflags;
+
+		spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
+
 		if (HAS_PCH_SPLIT(dev))
-			ironlake_enable_graphics_irq(dev_priv, GT_PIPE_NOTIFY);
+			ironlake_enable_graphics_irq(dev_priv,
+						     GT_PIPE_NOTIFY | GT_USER_INTERRUPT);
 		else
 			i915_enable_irq(dev_priv, I915_USER_INTERRUPT);
+
+		spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
 	}
-	spin_unlock_irqrestore(&dev_priv->user_irq_lock, irqflags);
 }
 
 static void
-render_ring_put_user_irq(struct intel_ring_buffer *ring)
+render_ring_put_irq(struct intel_ring_buffer *ring)
 {
 	struct drm_device *dev = ring->dev;
-	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
-	unsigned long irqflags;
 
-	spin_lock_irqsave(&dev_priv->user_irq_lock, irqflags);
-	BUG_ON(dev->irq_enabled && ring->user_irq_refcount <= 0);
-	if (dev->irq_enabled && (--ring->user_irq_refcount == 0)) {
+	BUG_ON(dev->irq_enabled && ring->irq_refcount == 0);
+	if (dev->irq_enabled && --ring->irq_refcount == 0) {
+		drm_i915_private_t *dev_priv = dev->dev_private;
+		unsigned long irqflags;
+
+		spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
 		if (HAS_PCH_SPLIT(dev))
-			ironlake_disable_graphics_irq(dev_priv, GT_PIPE_NOTIFY);
+			ironlake_disable_graphics_irq(dev_priv,
+						      GT_USER_INTERRUPT |
+						      GT_PIPE_NOTIFY);
 		else
 			i915_disable_irq(dev_priv, I915_USER_INTERRUPT);
+		spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
 	}
-	spin_unlock_irqrestore(&dev_priv->user_irq_lock, irqflags);
 }
 
 void intel_ring_setup_status_page(struct intel_ring_buffer *ring)
@@ -459,6 +532,9 @@ bsd_ring_flush(struct intel_ring_buffer *ring,
 	       u32     invalidate_domains,
 	       u32     flush_domains)
 {
+	if ((flush_domains & I915_GEM_DOMAIN_RENDER) == 0)
+		return;
+
 	if (intel_ring_begin(ring, 2) == 0) {
 		intel_ring_emit(ring, MI_FLUSH);
 		intel_ring_emit(ring, MI_NOOP);
@@ -491,20 +567,45 @@ ring_add_request(struct intel_ring_buffer *ring,
 }
 
 static void
-bsd_ring_get_user_irq(struct intel_ring_buffer *ring)
+ring_get_irq(struct intel_ring_buffer *ring, u32 flag)
 {
-	/* do nothing */
+	struct drm_device *dev = ring->dev;
+
+	if (dev->irq_enabled && ++ring->irq_refcount == 1) {
+		drm_i915_private_t *dev_priv = dev->dev_private;
+		unsigned long irqflags;
+
+		spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
+		ironlake_enable_graphics_irq(dev_priv, flag);
+		spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
+	}
 }
+
 static void
-bsd_ring_put_user_irq(struct intel_ring_buffer *ring)
+ring_put_irq(struct intel_ring_buffer *ring, u32 flag)
 {
-	/* do nothing */
+	struct drm_device *dev = ring->dev;
+
+	if (dev->irq_enabled && --ring->irq_refcount == 0) {
+		drm_i915_private_t *dev_priv = dev->dev_private;
+		unsigned long irqflags;
+
+		spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
+		ironlake_disable_graphics_irq(dev_priv, flag);
+		spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
+	}
 }
 
-static u32
-ring_status_page_get_seqno(struct intel_ring_buffer *ring)
+
+static void
+bsd_ring_get_irq(struct intel_ring_buffer *ring)
 {
-	return intel_read_status_page(ring, I915_GEM_HWS_INDEX);
+    ring_get_irq(ring, GT_BSD_USER_INTERRUPT);
+}
+static void
+bsd_ring_put_irq(struct intel_ring_buffer *ring)
+{
+    ring_put_irq(ring, GT_BSD_USER_INTERRUPT);
 }
 
 static int
@@ -817,9 +918,9 @@ static const struct intel_ring_buffer render_ring = {
 	.write_tail		= ring_write_tail,
 	.flush			= render_ring_flush,
 	.add_request		= render_ring_add_request,
-	.get_seqno		= render_ring_get_seqno,
-	.user_irq_get		= render_ring_get_user_irq,
-	.user_irq_put		= render_ring_put_user_irq,
+	.get_seqno		= ring_get_seqno,
+	.irq_get		= render_ring_get_irq,
+	.irq_put		= render_ring_put_irq,
 	.dispatch_execbuffer	= render_ring_dispatch_execbuffer,
        .cleanup			= render_ring_cleanup,
 };
@@ -835,9 +936,9 @@ static const struct intel_ring_buffer bsd_ring = {
 	.write_tail		= ring_write_tail,
 	.flush			= bsd_ring_flush,
 	.add_request		= ring_add_request,
-	.get_seqno		= ring_status_page_get_seqno,
-	.user_irq_get		= bsd_ring_get_user_irq,
-	.user_irq_put		= bsd_ring_put_user_irq,
+	.get_seqno		= ring_get_seqno,
+	.irq_get		= bsd_ring_get_irq,
+	.irq_put		= bsd_ring_put_irq,
 	.dispatch_execbuffer	= ring_dispatch_execbuffer,
 };
 
@@ -868,6 +969,9 @@ static void gen6_ring_flush(struct intel_ring_buffer *ring,
 			    u32 invalidate_domains,
 			    u32 flush_domains)
 {
+	if ((flush_domains & I915_GEM_DOMAIN_RENDER) == 0)
+		return;
+
 	if (intel_ring_begin(ring, 4) == 0) {
 		intel_ring_emit(ring, MI_FLUSH_DW);
 		intel_ring_emit(ring, 0);
@@ -895,33 +999,46 @@ gen6_ring_dispatch_execbuffer(struct intel_ring_buffer *ring,
        return 0;
 }
 
+static void
+gen6_bsd_ring_get_irq(struct intel_ring_buffer *ring)
+{
+    ring_get_irq(ring, GT_GEN6_BSD_USER_INTERRUPT);
+}
+
+static void
+gen6_bsd_ring_put_irq(struct intel_ring_buffer *ring)
+{
+    ring_put_irq(ring, GT_GEN6_BSD_USER_INTERRUPT);
+}
+
 /* ring buffer for Video Codec for Gen6+ */
 static const struct intel_ring_buffer gen6_bsd_ring = {
-       .name			= "gen6 bsd ring",
-       .id			= RING_BSD,
-       .mmio_base		= GEN6_BSD_RING_BASE,
-       .size			= 32 * PAGE_SIZE,
-       .init			= init_ring_common,
-       .write_tail		= gen6_bsd_ring_write_tail,
-       .flush			= gen6_ring_flush,
-       .add_request		= ring_add_request,
-       .get_seqno		= ring_status_page_get_seqno,
-       .user_irq_get		= bsd_ring_get_user_irq,
-       .user_irq_put		= bsd_ring_put_user_irq,
-       .dispatch_execbuffer	= gen6_ring_dispatch_execbuffer,
+	.name			= "gen6 bsd ring",
+	.id			= RING_BSD,
+	.mmio_base		= GEN6_BSD_RING_BASE,
+	.size			= 32 * PAGE_SIZE,
+	.init			= init_ring_common,
+	.write_tail		= gen6_bsd_ring_write_tail,
+	.flush			= gen6_ring_flush,
+	.add_request		= gen6_add_request,
+	.get_seqno		= ring_get_seqno,
+	.irq_get		= gen6_bsd_ring_get_irq,
+	.irq_put		= gen6_bsd_ring_put_irq,
+	.dispatch_execbuffer	= gen6_ring_dispatch_execbuffer,
 };
 
 /* Blitter support (SandyBridge+) */
 
 static void
-blt_ring_get_user_irq(struct intel_ring_buffer *ring)
+blt_ring_get_irq(struct intel_ring_buffer *ring)
 {
-	/* do nothing */
+    ring_get_irq(ring, GT_BLT_USER_INTERRUPT);
 }
+
 static void
-blt_ring_put_user_irq(struct intel_ring_buffer *ring)
+blt_ring_put_irq(struct intel_ring_buffer *ring)
 {
-	/* do nothing */
+    ring_put_irq(ring, GT_BLT_USER_INTERRUPT);
 }
 
 
@@ -994,6 +1111,9 @@ static void blt_ring_flush(struct intel_ring_buffer *ring,
 			   u32 invalidate_domains,
 			   u32 flush_domains)
 {
+	if ((flush_domains & I915_GEM_DOMAIN_RENDER) == 0)
+		return;
+
 	if (blt_ring_begin(ring, 4) == 0) {
 		intel_ring_emit(ring, MI_FLUSH_DW);
 		intel_ring_emit(ring, 0);
@@ -1003,30 +1123,6 @@ static void blt_ring_flush(struct intel_ring_buffer *ring,
 	}
 }
 
-static int
-blt_ring_add_request(struct intel_ring_buffer *ring,
-		     u32 *result)
-{
-	u32 seqno;
-	int ret;
-
-	ret = blt_ring_begin(ring, 4);
-	if (ret)
-		return ret;
-
-	seqno = i915_gem_get_seqno(ring->dev);
-
-	intel_ring_emit(ring, MI_STORE_DWORD_INDEX);
-	intel_ring_emit(ring, I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
-	intel_ring_emit(ring, seqno);
-	intel_ring_emit(ring, MI_USER_INTERRUPT);
-	intel_ring_advance(ring);
-
-	DRM_DEBUG_DRIVER("%s %d\n", ring->name, seqno);
-	*result = seqno;
-	return 0;
-}
-
 static void blt_ring_cleanup(struct intel_ring_buffer *ring)
 {
 	if (!ring->private)
@@ -1045,10 +1141,10 @@ static const struct intel_ring_buffer gen6_blt_ring = {
        .init			= blt_ring_init,
        .write_tail		= ring_write_tail,
        .flush			= blt_ring_flush,
-       .add_request		= blt_ring_add_request,
-       .get_seqno		= ring_status_page_get_seqno,
-       .user_irq_get		= blt_ring_get_user_irq,
-       .user_irq_put		= blt_ring_put_user_irq,
+       .add_request		= gen6_add_request,
+       .get_seqno		= ring_get_seqno,
+       .irq_get			= blt_ring_get_irq,
+       .irq_put			= blt_ring_put_irq,
        .dispatch_execbuffer	= gen6_ring_dispatch_execbuffer,
        .cleanup			= blt_ring_cleanup,
 };
@@ -1056,36 +1152,43 @@ static const struct intel_ring_buffer gen6_blt_ring = {
 int intel_init_render_ring_buffer(struct drm_device *dev)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct intel_ring_buffer *ring = &dev_priv->ring[RCS];
 
-	dev_priv->render_ring = render_ring;
+	*ring = render_ring;
+	if (INTEL_INFO(dev)->gen >= 6) {
+		ring->add_request = gen6_add_request;
+	} else if (HAS_PIPE_CONTROL(dev)) {
+		ring->add_request = pc_render_add_request;
+		ring->get_seqno = pc_render_get_seqno;
+	}
 
 	if (!I915_NEED_GFX_HWS(dev)) {
-		dev_priv->render_ring.status_page.page_addr
-			= dev_priv->status_page_dmah->vaddr;
-		memset(dev_priv->render_ring.status_page.page_addr,
-				0, PAGE_SIZE);
+		ring->status_page.page_addr = dev_priv->status_page_dmah->vaddr;
+		memset(ring->status_page.page_addr, 0, PAGE_SIZE);
 	}
 
-	return intel_init_ring_buffer(dev, &dev_priv->render_ring);
+	return intel_init_ring_buffer(dev, ring);
 }
 
 int intel_init_bsd_ring_buffer(struct drm_device *dev)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct intel_ring_buffer *ring = &dev_priv->ring[VCS];
 
 	if (IS_GEN6(dev))
-		dev_priv->bsd_ring = gen6_bsd_ring;
+		*ring = gen6_bsd_ring;
 	else
-		dev_priv->bsd_ring = bsd_ring;
+		*ring = bsd_ring;
 
-	return intel_init_ring_buffer(dev, &dev_priv->bsd_ring);
+	return intel_init_ring_buffer(dev, ring);
 }
 
 int intel_init_blt_ring_buffer(struct drm_device *dev)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct intel_ring_buffer *ring = &dev_priv->ring[BCS];
 
-	dev_priv->blt_ring = gen6_blt_ring;
+	*ring = gen6_blt_ring;
 
-	return intel_init_ring_buffer(dev, &dev_priv->blt_ring);
+	return intel_init_ring_buffer(dev, ring);
 }