[Intel-gfx] [PATCH] drm/i915: Initialize ring->obj last and use it as a marker

[Chris Wilson]

Use the assignment of ring->obj as a marker that the ring is active, and
so be careful not to initialise that value too early in case we need to
perform some workarounds that would ordinarily require touching the ring
whilst prepping the object.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_drv.c         |   12 +++++++-----
 drivers/gpu/drm/i915/intel_ringbuffer.c |   20 ++++++++++++--------
 drivers/gpu/drm/i915/intel_ringbuffer.h |    3 ++-
 3 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index ccfdc81..6019caa 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -838,15 +838,17 @@ int i915_reset(struct drm_device *dev, u8 flags)
 	 */
 	if (drm_core_check_feature(dev, DRIVER_MODESET) ||
 			!dev_priv->mm.suspended) {
+		int i;
+
 		dev_priv->mm.suspended = 0;
 
 		i915_gem_init_swizzling(dev);
 
-		dev_priv->ring[RCS].init(&dev_priv->ring[RCS]);
-		if (HAS_BSD(dev))
-		    dev_priv->ring[VCS].init(&dev_priv->ring[VCS]);
-		if (HAS_BLT(dev))
-		    dev_priv->ring[BCS].init(&dev_priv->ring[BCS]);
+		for (i = 0; i < I915_NUM_RINGS; i++) {
+			if (dev_priv->ring[i].obj)
+				dev_priv->ring[i].init(&dev_priv->ring[i],
+						       dev_priv->ring[i].obj);
+		}
 
 		i915_gem_init_ppgtt(dev);
 
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 6c14457..9bd659c 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -247,10 +247,10 @@ u32 intel_ring_get_active_head(struct intel_ring_buffer *ring)
 	return I915_READ(acthd_reg);
 }
 
-static int init_ring_common(struct intel_ring_buffer *ring)
+static int init_ring_common(struct intel_ring_buffer *ring,
+			    struct drm_i915_gem_object *obj)
 {
 	drm_i915_private_t *dev_priv = ring->dev->dev_private;
-	struct drm_i915_gem_object *obj = ring->obj;
 	u32 head;
 
 	/* Stop the ring if it's running. */
@@ -377,11 +377,16 @@ cleanup_pipe_control(struct intel_ring_buffer *ring)
 	ring->private = NULL;
 }
 
-static int init_render_ring(struct intel_ring_buffer *ring)
+static int init_render_ring(struct intel_ring_buffer *ring,
+			    struct drm_i915_gem_object *obj)
 {
 	struct drm_device *dev = ring->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	int ret = init_ring_common(ring);
+	int ret;
+
+	ret = init_ring_common(ring, obj);
+	if (ret)
+		return ret;
 
 	if (INTEL_INFO(dev)->gen > 3) {
 		int mode = VS_TIMER_DISPATCH << 16 | VS_TIMER_DISPATCH;
@@ -919,8 +924,6 @@ int intel_init_ring_buffer(struct drm_device *dev,
 		goto err_hws;
 	}
 
-	ring->obj = obj;
-
 	ret = i915_gem_object_pin(obj, PAGE_SIZE, true);
 	if (ret)
 		goto err_unref;
@@ -939,7 +942,8 @@ int intel_init_ring_buffer(struct drm_device *dev,
 	}
 
 	ring->virtual_start = ring->map.handle;
-	ret = ring->init(ring);
+
+	ret = ring->init(ring, obj);
 	if (ret)
 		goto err_unmap;
 
@@ -951,6 +955,7 @@ int intel_init_ring_buffer(struct drm_device *dev,
 	if (IS_I830(ring->dev))
 		ring->effective_size -= 128;
 
+	ring->obj = obj;
 	return 0;
 
 err_unmap:
@@ -959,7 +964,6 @@ err_unpin:
 	i915_gem_object_unpin(obj);
 err_unref:
 	drm_gem_object_unreference(&obj->base);
-	ring->obj = NULL;
 err_hws:
 	cleanup_status_page(ring);
 	return ret;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 06a66ad..c3c464d 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -66,7 +66,8 @@ struct  intel_ring_buffer {
 	bool __must_check (*irq_get)(struct intel_ring_buffer *ring);
 	void		(*irq_put)(struct intel_ring_buffer *ring);
 
-	int		(*init)(struct intel_ring_buffer *ring);
+	int		(*init)(struct intel_ring_buffer *ring,
+				struct drm_i915_gem_object *obj);
 
 	void		(*write_tail)(struct intel_ring_buffer *ring,
 				      u32 value);
-- 
1.7.10