From: Ankitprasad Sharma <ankitprasad.r.sharma@xxxxxxxxx>
This patch adds support for clearing buffer objects via CPU/GTT. This
is particularly useful for clearing out the non shmem backed objects.
Currently intend to use this only for buffers allocated from stolen
region.
v2: Added kernel doc for i915_gem_clear_object(), corrected/removed
variable assignments (Tvrtko)
v3: Map object page by page to the gtt if the pinning of the whole object
to the ggtt fails, Corrected function name (Chris)
v4: Clear the buffer page by page, and not map the whole object in the gtt
aperture. Use i915 wrapper function in place of drm_mm_insert_node_in_range.
Testcase: igt/gem_stolen
Signed-off-by: Ankitprasad Sharma <ankitprasad.r.sharma@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.h | 1 +
drivers/gpu/drm/i915/i915_gem.c | 44 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 45 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index a10b866..e195fee 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2897,6 +2897,7 @@ int i915_gem_obj_prepare_shmem_read(struct drm_i915_gem_object *obj,
int *needs_clflush);
int __must_check i915_gem_object_get_pages(struct drm_i915_gem_object *obj);
+int i915_gem_object_clear(struct drm_i915_gem_object *obj);
static inline int __sg_page_count(struct scatterlist *sg)
{
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 46c1e75..e50a91b 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5293,3 +5293,47 @@ fail:
drm_gem_object_unreference(&obj->base);
return ERR_PTR(ret);
}
+
+/**
+ * i915_gem_object_clear() - Clear buffer object via CPU/GTT
+ * @obj: Buffer object to be cleared
+ *
+ * Return: 0 - success, non-zero - failure
+ */
+int i915_gem_object_clear(struct drm_i915_gem_object *obj)
+{
+ int ret, i;
+ char __iomem *base;
+ size_t size = obj->base.size;
+ struct drm_i915_private *i915 = to_i915(obj->base.dev);
+ struct drm_mm_node node;
+
+ lockdep_assert_held(&obj->base.dev->struct_mutex);
+ memset(&node, 0, sizeof(node));
+ ret = i915_gem_insert_node_in_range(i915, &node, 4096, 0,
+ 0, i915->gtt.mappable_end);
+ if (ret)
+ goto out;
+
+ i915_gem_object_pin_pages(obj);
+ base = io_mapping_map_wc(i915->gtt.mappable, node.start);
+ for (i = 0; i < size/PAGE_SIZE; i++) {
+ wmb();
+ i915->gtt.base.insert_page(&i915->gtt.base,
+ i915_gem_object_get_dma_address(obj, i),
+ node.start,
+ I915_CACHE_NONE, 0);
+ wmb();
+ memset_io(base, 0, 4096);
+ }
+
+ wmb();
+ io_mapping_unmap(base);
+ i915->gtt.base.clear_range(&i915->gtt.base,
+ node.start, node.size,
+ true);
+ drm_mm_remove_node(&node);
+ i915_gem_object_unpin_pages(obj);
+out:
+ return ret;
+}
--
1.9.1
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