From: Ankitprasad Sharma <ankitprasad.r.sha...@intel.com>
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.
v5: Use renamed wrapper function for drm_mm_insert_node_in_range,
updated barrier positioning (Chris)
v6: Use PAGE_SIZE instead of 4096, use get_pages call before pinning pages
(Tvrtko)
v7: Fixed the onion (undo operation in reverse order) (Chris)
v8: Rebase (Ankit)
Testcase: igt/gem_stolen
Signed-off-by: Ankitprasad Sharma <ankitprasad.r.sha...@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
Reviewed-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_drv.h | 1 +
drivers/gpu/drm/i915/i915_gem.c | 45 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 46 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 883b706..3e41ac6 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2968,6 +2968,7 @@ 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 0b7ce9d..8adb962 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5446,3 +5446,48 @@ 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)
+{
+ struct drm_i915_private *i915 = to_i915(obj->base.dev);
+ struct i915_ggtt *ggtt = &i915->ggtt;
+ struct drm_mm_node node;
+ char __iomem *base;
+ uint64_t size = obj->base.size;
+ int ret, i;
+
+ lockdep_assert_held(&obj->base.dev->struct_mutex);
+ ret = insert_mappable_node(i915, &node, PAGE_SIZE);
+ if (ret)
+ return ret;
+
+ ret = i915_gem_object_get_pages(obj);
+ if (ret)
+ goto err_remove_node;
+
+ i915_gem_object_pin_pages(obj);
+ base = io_mapping_map_wc(ggtt->mappable, node.start);
+
+ for (i = 0; i < size/PAGE_SIZE; i++) {
+ ggtt->base.insert_page(&ggtt->base,
+ i915_gem_object_get_dma_address(obj, i),
+ node.start, I915_CACHE_NONE, 0);
+ wmb(); /* flush modifications to the GGTT (insert_page) */
+ memset_io(base, 0, PAGE_SIZE);
+ wmb(); /* flush the write before we modify the GGTT */
+ }
+
+ io_mapping_unmap(base);
+ ggtt->base.clear_range(&ggtt->base, node.start, node.size, true);
+ i915_gem_object_unpin_pages(obj);
+
+err_remove_node:
+ remove_mappable_node(&node);
+ return ret;
+}
--
1.9.1
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