1 files changed, 39 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_scatterlist.c b/drivers/gpu/drm/i915/i915_scatterlist.c
new file mode 100644
index 000000000000..cc6b3846a8c7
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_scatterlist.c
@@ -0,0 +1,39 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2016 Intel Corporation
+ */
+
+#include "i915_scatterlist.h"
+
+bool 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 false;
+
+	if (sg_alloc_table(&new_st, orig_st->nents, GFP_KERNEL | __GFP_NOWARN))
+		return false;
+
+	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);
+		sg_dma_address(new_sg) = sg_dma_address(sg);
+		sg_dma_len(new_sg) = sg_dma_len(sg);
+
+		new_sg = sg_next(new_sg);
+	}
+	GEM_BUG_ON(new_sg); /* Should walk exactly nents and hit the end */
+
+	sg_free_table(orig_st);
+
+	*orig_st = new_st;
+	return true;
+}
+
+#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
+#include "selftests/scatterlist.c"
+#endif