i915_scatterlist.c revision 1.1 
1/*
2 * SPDX-License-Identifier: MIT
3 *
4 * Copyright �� 2016 Intel Corporation
5 */
6
7#include "i915_scatterlist.h"
8
9bool i915_sg_trim(struct sg_table *orig_st)
10{
11	struct sg_table new_st;
12	struct scatterlist *sg, *new_sg;
13	unsigned int i;
14
15	if (orig_st->nents == orig_st->orig_nents)
16		return false;
17
18	if (sg_alloc_table(&new_st, orig_st->nents, GFP_KERNEL | __GFP_NOWARN))
19		return false;
20
21	new_sg = new_st.sgl;
22	for_each_sg(orig_st->sgl, sg, orig_st->nents, i) {
23		sg_set_page(new_sg, sg_page(sg), sg->length, 0);
24		sg_dma_address(new_sg) = sg_dma_address(sg);
25		sg_dma_len(new_sg) = sg_dma_len(sg);
26
27		new_sg = sg_next(new_sg);
28	}
29	GEM_BUG_ON(new_sg); /* Should walk exactly nents and hit the end */
30
31	sg_free_table(orig_st);
32
33	*orig_st = new_st;
34	return true;
35}
36
37#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
38#include "selftests/scatterlist.c"
39#endif
40