[PATCH 4/6] drm/i915: Add an interface to dynamically change the cache level

[Eric Anholt <eric@anholt.net>]

From: Chris Wilson <chris@chris-wilson.co.uk>

[v2: Don't forget that when going from cached to uncached, we haven't
been tracking the write domain from the CPU perspective, since we
haven't needed it for GPU coherency.]

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>
---
 drivers/gpu/drm/i915/i915_drv.h         |    6 ++++-
 drivers/gpu/drm/i915/i915_gem.c         |   35 ++++++++++++++++++++++++++++++-
 drivers/gpu/drm/i915/i915_gem_gtt.c     |    8 ++++--
 drivers/gpu/drm/i915/intel_ringbuffer.c |    6 +++-
 4 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 6d98e0e..e38765d 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1190,9 +1190,13 @@ void i915_gem_release(struct drm_device *dev, struct drm_file *file);
 uint32_t
 i915_gem_get_unfenced_gtt_alignment(struct drm_i915_gem_object *obj);
 
+int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
+				    enum i915_cache_level cache_level);
+
 /* i915_gem_gtt.c */
 void i915_gem_restore_gtt_mappings(struct drm_device *dev);
-int __must_check i915_gem_gtt_bind_object(struct drm_i915_gem_object *obj);
+int __must_check i915_gem_gtt_bind_object(struct drm_i915_gem_object *obj,
+					  enum i915_cache_level cache_level);
 void i915_gem_gtt_unbind_object(struct drm_i915_gem_object *obj);
 
 /* i915_gem_evict.c */
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index fa483d8..8389b03 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2831,7 +2831,7 @@ i915_gem_object_bind_to_gtt(struct drm_i915_gem_object *obj,
 		return ret;
 	}
 
-	ret = i915_gem_gtt_bind_object(obj);
+	ret = i915_gem_gtt_bind_object(obj, obj->cache_level);
 	if (ret) {
 		i915_gem_object_put_pages_gtt(obj);
 		drm_mm_put_block(obj->gtt_space);
@@ -3002,6 +3002,39 @@ i915_gem_object_set_to_gtt_domain(struct drm_i915_gem_object *obj, bool write)
 	return 0;
 }
 
+int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
+				    enum i915_cache_level cache_level)
+{
+	int ret;
+
+	if (obj->cache_level == cache_level)
+		return 0;
+
+	if (obj->gtt_space) {
+		ret = i915_gem_object_flush_gpu(obj);
+		if (ret)
+			return ret;
+
+		ret = i915_gem_gtt_bind_object(obj, cache_level);
+		if (ret)
+			return ret;
+	}
+
+	if (cache_level == I915_CACHE_NONE) {
+		/* If we're coming frm LLC cached, then we haven't
+		 * actually been tracking whether the data is in the
+		 * CPU cache or not, since we only allow one bit set
+		 * in obj->write_domain.  Just set it to the CPU cache
+		 * for now.
+		 */
+		BUG_ON(obj->base.write_domain & I915_GEM_GPU_DOMAINS);
+		obj->base.write_domain = I915_GEM_DOMAIN_CPU;
+	}
+
+	obj->cache_level = cache_level;
+	return 0;
+}
+
 /*
  * Prepare buffer for display plane. Use uninterruptible for possible flush
  * wait, as in modesetting process we're not supposed to be interrupted.
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index af3c0e6..47d8bad 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -70,10 +70,12 @@ void i915_gem_restore_gtt_mappings(struct drm_device *dev)
 	intel_gtt_chipset_flush();
 }
 
-int i915_gem_gtt_bind_object(struct drm_i915_gem_object *obj)
+int i915_gem_gtt_bind_object(struct drm_i915_gem_object *obj,
+			     enum i915_cache_level cache_level)
 {
 	struct drm_device *dev = obj->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	uint32_t agp_type = cache_level_to_agp_type(cache_level);
 	int ret;
 
 	if (dev_priv->mm.gtt->needs_dmar) {
@@ -87,12 +89,12 @@ int i915_gem_gtt_bind_object(struct drm_i915_gem_object *obj)
 		intel_gtt_insert_sg_entries(obj->sg_list,
 					    obj->num_sg,
 					    obj->gtt_space->start >> PAGE_SHIFT,
-					    cache_level_to_agp_type(obj->cache_level));
+					    agp_type);
 	} else
 		intel_gtt_insert_pages(obj->gtt_space->start >> PAGE_SHIFT,
 				       obj->base.size >> PAGE_SHIFT,
 				       obj->pages,
-				       cache_level_to_agp_type(obj->cache_level));
+				       agp_type);
 
 	return 0;
 }
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index bb18dfb..6d25e79 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -236,7 +236,8 @@ init_pipe_control(struct intel_ring_buffer *ring)
 		ret = -ENOMEM;
 		goto err;
 	}
-	obj->cache_level = I915_CACHE_LLC;
+
+	i915_gem_object_set_cache_level(obj, I915_CACHE_LLC);
 
 	ret = i915_gem_object_pin(obj, 4096, true);
 	if (ret)
@@ -759,7 +760,8 @@ static int init_status_page(struct intel_ring_buffer *ring)
 		ret = -ENOMEM;
 		goto err;
 	}
-	obj->cache_level = I915_CACHE_LLC;
+
+	i915_gem_object_set_cache_level(obj, I915_CACHE_LLC);
 
 	ret = i915_gem_object_pin(obj, 4096, true);
 	if (ret != 0) {
-- 
1.7.4.1