drm/i915: Use radixtree to jump start intel_partial_pages()

We can use the radixtree index of the obj->pages to find the start
position of the desired partial range.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-11-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 2bbbda1..b3f341f 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -3584,35 +3584,47 @@ intel_partial_pages(const struct i915_ggtt_view *view,
                    struct drm_i915_gem_object *obj)
 {
        struct sg_table *st;
-       struct scatterlist *sg;
-       struct sg_page_iter obj_sg_iter;
+       struct scatterlist *sg, *iter;
+       unsigned int count = view->params.partial.size;
+       unsigned int offset;
        int ret = -ENOMEM;
 
        st = kmalloc(sizeof(*st), GFP_KERNEL);
        if (!st)
                goto err_st_alloc;
 
-       ret = sg_alloc_table(st, view->params.partial.size, GFP_KERNEL);
+       ret = sg_alloc_table(st, count, GFP_KERNEL);
        if (ret)
                goto err_sg_alloc;
 
+       iter = i915_gem_object_get_sg(obj,
+                                     view->params.partial.offset,
+                                     &offset);
+       GEM_BUG_ON(!iter);
+
        sg = st->sgl;
        st->nents = 0;
-       for_each_sg_page(obj->pages->sgl, &obj_sg_iter, obj->pages->nents,
-               view->params.partial.offset)
-       {
-               if (st->nents >= view->params.partial.size)
-                       break;
+       do {
+               unsigned int len;
 
-               sg_set_page(sg, NULL, PAGE_SIZE, 0);
-               sg_dma_address(sg) = sg_page_iter_dma_address(&obj_sg_iter);
-               sg_dma_len(sg) = PAGE_SIZE;
+               len = min(iter->length - (offset << PAGE_SHIFT),
+                         count << PAGE_SHIFT);
+               sg_set_page(sg, NULL, len, 0);
+               sg_dma_address(sg) =
+                       sg_dma_address(iter) + (offset << PAGE_SHIFT);
+               sg_dma_len(sg) = len;
 
-               sg = sg_next(sg);
                st->nents++;
-       }
+               count -= len >> PAGE_SHIFT;
+               if (count == 0) {
+                       sg_mark_end(sg);
+                       return st;
+               }
 
-       return st;
+               sg = __sg_next(sg);
+               iter = __sg_next(iter);
+               offset = 0;
+       } while (1);
 
 err_sg_alloc:
        kfree(st);