diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index d2ad73d0b5b9..1c20edba7f2a 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -2232,6 +2232,30 @@ static unsigned int swiotlb_max_size(void) #endif } +static void i915_sg_trim(struct sg_table *orig_st) +{ + struct sg_table new_st; + struct scatterlist *sg, *new_sg; + unsigned int i; + + if (orig_st->nents == orig_st->orig_nents) + return; + + if (sg_alloc_table(&new_st, orig_st->nents, GFP_KERNEL)) + return; + + new_sg = new_st.sgl; + for_each_sg(orig_st->sgl, sg, orig_st->nents, i) { + sg_set_page(new_sg, sg_page(sg), sg->length, 0); + /* called before being DMA mapped, no need to copy sg->dma_* */ + new_sg = sg_next(new_sg); + } + + sg_free_table(orig_st); + + *orig_st = new_st; +} + static struct sg_table * i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj) { @@ -2317,6 +2341,9 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj) if (sg) /* loop terminated early; short sg table */ sg_mark_end(sg); + /* Trim unused sg entries to avoid wasting memory. */ + i915_sg_trim(st); + ret = i915_gem_gtt_prepare_pages(obj, st); if (ret) goto err_pages;