From 341be1cd61826a8a143c2fc4cf3e418d1d5efc02 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 10 Jun 2016 14:23:00 +0530 Subject: [PATCH] drm/i915: Introduce i915_gem_object_get_dma_address() 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 Signed-off-by: Ankitprasad Sharma Reviewed-by: Tvrtko Ursulin Signed-off-by: Tvrtko Ursulin --- 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 53d9e3fab489..0349c5fe946c 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -3118,6 +3118,23 @@ 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) { -- 2.20.1