[PATCH 13/18] drm/i915: Introduce i915_gem_object_create_stolen()

Chris Wilson
2012-10-19T17:05:00Z

Allow for the creation of GEM objects backed by stolen memory. As these
are not backed by ordinary pages, we create a fake dma mapping and store
the address in the scatterlist rather than obj->pages.

v2: Mark _i915_gem_object_create_stolen() as static, as noticed by Jesse
Barnes.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
---
drivers/gpu/drm/i915/i915_drv.h | 3 +
drivers/gpu/drm/i915/i915_gem.c | 1 +
drivers/gpu/drm/i915/i915_gem_stolen.c | 122 ++++++++++++++++++++++++++++++++
3 files changed, 126 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 6b893c7..5a0e0cd 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1526,6 +1526,9 @@ int i915_gem_init_stolen(struct drm_device *dev);
int i915_gem_stolen_setup_compression(struct drm_device *dev);
void i915_gem_stolen_cleanup_compression(struct drm_device *dev);
void i915_gem_cleanup_stolen(struct drm_device *dev);
+struct drm_i915_gem_object *
+i915_gem_object_create_stolen(struct drm_device *dev, u32 size);
+void i915_gem_object_release_stolen(struct drm_i915_gem_object *obj);

/* i915_gem_tiling.c */
void i915_gem_detect_bit_6_swizzle(struct drm_device *dev);
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d75c5c3..0349899 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3857,6 +3857,7 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
obj->pages_pin_count = 0;
i915_gem_object_put_pages(obj);
i915_gem_object_free_mmap_offset(obj);
+ i915_gem_object_release_stolen(obj);

BUG_ON(obj->pages);

diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index 68ef22a..86c4af4 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -204,3 +204,125 @@ int i915_gem_init_stolen(struct drm_device *dev)

return 0;
}
+
+static struct sg_table *
+i915_pages_create_for_stolen(struct drm_device *dev,
+ u32 offset, u32 size)
+{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ struct sg_table *st;
+ struct scatterlist *sg;
+
+ /* We hide that we have no struct page backing our stolen object
+ * by wrapping the contiguous physical allocation with a fake
+ * dma mapping in a single scatterlist.
+ */
+
+ st = kmalloc(sizeof(*st), GFP_KERNEL);
+ if (st == NULL)
+ return NULL;
+
+ if (!sg_alloc_table(st, 1, GFP_KERNEL)) {
+ kfree(st);
+ return NULL;
+ }
+
+ sg = st->sgl;
+ sg->offset = offset;
+ sg->length = size;
+
+ sg_dma_address(sg) = dev_priv->mm.stolen_base + offset;
+ sg_dma_len(sg) = size;
+
+ return st;
+}
+
+static int i915_gem_object_get_pages_stolen(struct drm_i915_gem_object *obj)
+{
+ BUG();
+ return -EINVAL;
+}
+
+static void i915_gem_object_put_pages_stolen(struct drm_i915_gem_object *obj)
+{
+ /* Should only be called during free */
+ sg_free_table(obj->pages);
+ kfree(obj->pages);
+}
+
+static const struct drm_i915_gem_object_ops i915_gem_object_stolen_ops = {
+ .get_pages = i915_gem_object_get_pages_stolen,
+ .put_pages = i915_gem_object_put_pages_stolen,
+};
+
+static struct drm_i915_gem_object *
+_i915_gem_object_create_stolen(struct drm_device *dev,
+ struct drm_mm_node *stolen)
+{
+ struct drm_i915_gem_object *obj;
+
+ obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+ if (obj == NULL)
+ return NULL;
+
+ if (drm_gem_private_object_init(dev, &obj->base, stolen->size))
+ goto cleanup;
+
+ i915_gem_object_init(obj, &i915_gem_object_stolen_ops);
+
+ obj->pages = i915_pages_create_for_stolen(dev,
+ stolen->start, stolen->size);
+ if (obj->pages == NULL)
+ goto cleanup;
+
+ obj->has_dma_mapping = true;
+ obj->pages_pin_count = 1;
+ obj->stolen = stolen;
+
+ obj->base.write_domain = I915_GEM_DOMAIN_GTT;
+ obj->base.read_domains = I915_GEM_DOMAIN_GTT;
+ obj->cache_level = I915_CACHE_NONE;
+
+ return obj;
+
+cleanup:
+ kfree(obj);
+ return NULL;
+}
+
+struct drm_i915_gem_object *
+i915_gem_object_create_stolen(struct drm_device *dev, u32 size)
+{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ struct drm_i915_gem_object *obj;
+ struct drm_mm_node *stolen;
+
+ if (dev_priv->mm.stolen_base == 0)
+ return 0;
+
+ DRM_DEBUG_KMS("creating stolen object: size=%x\n", size);
+ if (size == 0)
+ return NULL;
+
+ stolen = drm_mm_search_free(&dev_priv->mm.stolen, size, 4096, 0);
+ if (stolen)
+ stolen = drm_mm_get_block(stolen, size, 4096);
+ if (stolen == NULL)
+ return NULL;
+
+ obj = _i915_gem_object_create_stolen(dev, stolen);
+ if (obj)
+ return obj;
+
+ drm_mm_put_block(stolen);
+ return NULL;
+}
+
+void
+i915_gem_object_release_stolen(struct drm_i915_gem_object *obj)
+{
+ if (obj->stolen) {
+ drm_mm_put_block(obj->stolen);
+ obj->stolen = NULL;
+ }
+}
--
1.7.10.4