Index: sys/compat/linuxkpi/common/include/linux/scatterlist.h
===================================================================
--- sys/compat/linuxkpi/common/include/linux/scatterlist.h
+++ sys/compat/linuxkpi/common/include/linux/scatterlist.h
@@ -66,6 +66,10 @@
 	} internal;
 };
 
+struct sg_dma_page_iter {
+       struct sg_page_iter base;
+};
+
 #define	SCATTERLIST_MAX_SEGMENT	(-1U & ~(PAGE_SIZE - 1))
 
 #define	SG_MAX_SINGLE_ALLOC	(PAGE_SIZE / sizeof(struct scatterlist))
@@ -86,6 +90,9 @@
 	for (_sg_iter_init(sgl, iter, nents, pgoffset);			\
 	     (iter)->sg; _sg_iter_next(iter))
 
+#define for_each_sg_dma_page(sgl, iter, nents, pgoffset)		\
+	for_each_sg_page(sgl, &(iter)->base, nents, pgoffset)
+
 #define	for_each_sg(sglist, sg, sgmax, iter)				\
 	for (iter = 0, sg = (sglist); iter < (sgmax); iter++, sg = sg_next(sg))
 
@@ -427,6 +434,37 @@
 	return (1);
 }
 
+static int
+sg_dma_page_count(struct scatterlist *sg)
+{
+	return PAGE_ALIGN(sg->offset + sg_dma_len(sg)) >> PAGE_SHIFT;
+}
+
+static inline bool
+__sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter)
+{
+	struct sg_page_iter *piter = &dma_iter->base;
+
+	if (piter->internal.nents == 0)
+		return (0);
+	if (piter->sg == NULL)
+		return (0);
+
+	piter->sg_pgoffset += piter->internal.pg_advance;
+	piter->internal.pg_advance = 1;
+
+	while (piter->sg_pgoffset >= sg_dma_page_count(piter->sg)) {
+		piter->sg_pgoffset -= sg_dma_page_count(piter->sg);
+		piter->sg = sg_next(piter->sg);
+		if (--piter->internal.nents == 0)
+			return (0);
+		if (piter->sg == NULL)
+			return (0);
+	}
+
+	return (true);
+}
+
 static inline void
 _sg_iter_init(struct scatterlist *sgl, struct sg_page_iter *iter,
     unsigned int nents, unsigned long pgoffset)
@@ -443,8 +481,17 @@
 	}
 }
 
+/*
+ * Prevent api breakage by casting the itr
+ * argument to sg_page_iter. Newer drm code uses
+ * sg_dma_page_iter. This works because sg_dma_page_itr
+ * just wraps sg_page_iter.
+ */
+#define sg_page_iter_dma_address(itr) \
+	_sg_page_iter_dma_address((struct sg_page_iter *)itr)
+
 static inline dma_addr_t
-sg_page_iter_dma_address(struct sg_page_iter *spi)
+_sg_page_iter_dma_address(struct sg_page_iter *spi)
 {
 	return (spi->sg->dma_address + (spi->sg_pgoffset << PAGE_SHIFT));
 }