Commit 871dfbd6 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Allow compaction upto SWIOTLB max segment size 



commit 1625e7e5 ("drm/i915: make compact dma scatter lists creation
work with SWIOTLB backend") took a heavy handed approach to undo the
scatterlist compaction in the face of SWIOTLB. (The compaction hit a bug
whereby we tried to pass a segment larger than SWIOTLB could handle.) We
can be a little more intelligent and try compacting the scatterlist up
to the maximum SWIOTLB segment size (when using SWIOTLB).

v2: Tidy sg_mark_end() and cpp

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
CC: Imre Deak <imre.deak@intel.com>
CC: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161011082021.14606-2-chris@chris-wilson.co.uk
parent 465350d0

drivers/gpu/drm/i915/i915_gem.c

+18 −12
Original line number Diff line number Diff line
@@ -2208,6 +2208,15 @@ i915_gem_object_put_pages(struct drm_i915_gem_object *obj) 
	return 0;

}



static unsigned long swiotlb_max_size(void)

{

#if IS_ENABLED(CONFIG_SWIOTLB)

	return rounddown(swiotlb_nr_tbl() << IO_TLB_SHIFT, PAGE_SIZE);

#else

	return 0;

#endif

}



static int

i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)

{
@@ -2219,6 +2228,7 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj) 
	struct sgt_iter sgt_iter;

	struct page *page;

	unsigned long last_pfn = 0;	/* suppress gcc warning */

	unsigned long max_segment;

	int ret;

	gfp_t gfp;
@@ -2229,6 +2239,10 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj) 
	BUG_ON(obj->base.read_domains & I915_GEM_GPU_DOMAINS);

	BUG_ON(obj->base.write_domain & I915_GEM_GPU_DOMAINS);



	max_segment = swiotlb_max_size();

	if (!max_segment)

		max_segment = obj->base.size;



	st = kmalloc(sizeof(*st), GFP_KERNEL);

	if (st == NULL)

		return -ENOMEM;
@@ -2270,15 +2284,9 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj) 
				goto err_pages;

			}

		}

#ifdef CONFIG_SWIOTLB

		if (swiotlb_nr_tbl()) {

			st->nents++;

			sg_set_page(sg, page, PAGE_SIZE, 0);

			sg = sg_next(sg);

			continue;

		}

#endif

		if (!i || page_to_pfn(page) != last_pfn + 1) {

		if (!i ||

		    sg->length >= max_segment ||

		    page_to_pfn(page) != last_pfn + 1) {

			if (i)

				sg = sg_next(sg);

			st->nents++;
@@ -2291,9 +2299,7 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj) 
		/* Check that the i965g/gm workaround works. */

		WARN_ON((gfp & __GFP_DMA32) && (last_pfn >= 0x00100000UL));

	}

#ifdef CONFIG_SWIOTLB

	if (!swiotlb_nr_tbl())

#endif

	if (sg) /* loop terminated early; short sg table */

		sg_mark_end(sg);

	obj->pages = st;

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