From 871dfbd67d4ecbcc83fc9e80a310ca9bf3c44c40 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 11 Oct 2016 09:20:21 +0100 Subject: [PATCH] drm/i915: Allow compaction upto SWIOTLB max segment size commit 1625e7e549c5 ("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: Chris Wilson CC: Imre Deak CC: Daniel Vetter Cc: Konrad Rzeszutek Wilk Cc: Tvrtko Ursulin Reviewed-by: Tvrtko Ursulin Link: http://patchwork.freedesktop.org/patch/msgid/20161011082021.14606-2-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index ec0a314..9eb9ccd 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -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; -- 2.7.4