From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
This utility function is a companion to i915_gem_object_get_page() that
uses the same cached iterator for the scatterlist to perform fast
sequential lookup of the dma address associated with any page within the
object.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Ankitprasad Sharma <ankitprasad.r.sharma@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.h | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 747d2d8..7dc122f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2902,6 +2902,23 @@ static inline int __sg_page_count(struct scatterlist *sg)
struct page *
i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj, int n);
+static inline dma_addr_t
+i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj, int n)
+{
+ if (n < obj->get_page.last) {
+ obj->get_page.sg = obj->pages->sgl;
+ obj->get_page.last = 0;
+ }
+
+ while (obj->get_page.last + __sg_page_count(obj->get_page.sg) <= n) {
+ obj->get_page.last += __sg_page_count(obj->get_page.sg++);
+ if (unlikely(sg_is_chain(obj->get_page.sg)))
+ obj->get_page.sg = sg_chain_ptr(obj->get_page.sg);
+ }
+
+ return sg_dma_address(obj->get_page.sg) + ((n - obj->get_page.last) << PAGE_SHIFT);
+}
+
static inline struct page *
i915_gem_object_get_page(struct drm_i915_gem_object *obj, int n)
{
--
1.9.1
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