Index: sys/arm64/arm64/busdma_bounce.c
===================================================================
--- sys/arm64/arm64/busdma_bounce.c
+++ sys/arm64/arm64/busdma_bounce.c
@@ -131,6 +131,7 @@
 	struct bp_list	       bpages;
 	int		       pagesneeded;
 	int		       pagesreserved;
+	STAILQ_HEAD(bpagel, bounce_page) qbplist;
 	bus_dma_tag_t	       dmat;
 	struct memdesc	       mem;
 	bus_dmamap_callback_t *callback;
@@ -154,6 +155,8 @@
     int commit);
 static bus_addr_t add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map,
     vm_offset_t vaddr, bus_addr_t addr, bus_size_t size);
+static bus_addr_t add_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map,
+    vm_offset_t vaddr, bus_addr_t addr, bus_size_t size);
 static void free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage);
 int run_filter(bus_dma_tag_t dmat, bus_addr_t paddr);
 static bool _bus_dmamap_pagesneeded(bus_dma_tag_t dmat, bus_dmamap_t map,
@@ -394,6 +397,7 @@
 
 	/* Initialize the new map */
 	STAILQ_INIT(&map->bpages);
+	STAILQ_INIT(&map->qbplist);
 
 	return (map);
 }
@@ -496,6 +500,11 @@
 		CTR3(KTR_BUSDMA, "%s: tag %p error %d", __func__, dmat, EBUSY);
 		return (EBUSY);
 	}
+	if (!STAILQ_EMPTY(&map->qbplist)) {
+		/* Running a bounce_bus_dmamap_load_phys() operation. */
+		CTR3(KTR_BUSDMA, "%s: tag %p error %d", __func__, dmat, EBUSY);
+		return (EBUSY);
+	}
 	if (dmat->bounce_zone)
 		dmat->bounce_zone->map_count--;
 	free(map, M_DEVBUF);
@@ -814,6 +823,7 @@
 	bus_size_t sgsize;
 	bus_addr_t curaddr, sl_end;
 	int error;
+	bool first;
 
 	if (segs == NULL)
 		segs = dmat->segments;
@@ -830,6 +840,7 @@
 	sl = map->slist + map->sync_count - 1;
 	sl_end = 0;
 
+	first = true;
 	while (buflen > 0) {
 		curaddr = buf;
 		sgsize = MIN(buflen, dmat->common.maxsegsz);
@@ -846,8 +857,13 @@
 			    ("bounced buffer cannot have alignment bigger "
 			    "than PAGE_SIZE: %lu", dmat->common.alignment));
 			sgsize = MIN(sgsize, PAGE_SIZE - (curaddr & PAGE_MASK));
-			curaddr = add_bounce_page(dmat, map, 0, curaddr,
-			    sgsize);
+			if (first && dmat->common.nsegments == 1 &&
+			    map->pagesneeded > 1)
+				curaddr = add_bounce_pages(dmat, map, 0,
+				    curaddr, sgsize);
+			else
+				curaddr = add_bounce_page(dmat, map, 0, curaddr,
+				    sgsize);
 		} else if ((map->flags & DMAMAP_COHERENT) == 0) {
 			if (map->sync_count > 0)
 				sl_end = sl->paddr + sl->datacount;
@@ -872,6 +888,7 @@
 			break;
 		buf += sgsize;
 		buflen -= sgsize;
+		first = false;
 	}
 
 	/*
@@ -1237,6 +1254,31 @@
 	return (bz->sysctl_tree_top);
 }
 
+static void
+insert_bounce_page_sorted(struct bounce_zone *bz, struct bounce_page *bpage)
+{
+	struct bounce_page *bp, *bpp;
+
+	mtx_assert(&bounce_lock, MA_OWNED);
+
+	/* Sort by busaddr. */
+	bp = bpp = NULL;
+	STAILQ_FOREACH(bp, &bz->bounce_page_list, links) {
+		if (bpage->busaddr < bp->busaddr) {
+			if (bpp == NULL)
+				STAILQ_INSERT_HEAD(&bz->bounce_page_list,
+				    bpage, links);
+			else
+				STAILQ_INSERT_AFTER(&bz->bounce_page_list, bpp,
+				    bpage, links);
+			break;
+		}
+		bpp = bp;
+	}
+	if (bp == NULL)
+		STAILQ_INSERT_TAIL(&bz->bounce_page_list, bpage, links);
+}
+
 static int
 alloc_bounce_zone(bus_dma_tag_t dmat)
 {
@@ -1335,7 +1377,7 @@
 		}
 		bpage->busaddr = pmap_kextract(bpage->vaddr);
 		mtx_lock(&bounce_lock);
-		STAILQ_INSERT_TAIL(&bz->bounce_page_list, bpage, links);
+		insert_bounce_page_sorted(bz, bpage);
 		total_bpages++;
 		bz->total_bpages++;
 		bz->free_bpages++;
@@ -1365,6 +1407,92 @@
 	return (pages);
 }
 
+/*
+ * Special case of add_bounce_page(); in case of a single segment requested
+ * we try to find a contigous space of pages to accommodate the entire needs
+ * return the first and queue the others up in the map for add_bounce_page()
+ * to find them on the next iterations.
+ */
+static bus_addr_t
+add_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map, vm_offset_t vaddr,
+		bus_addr_t addr, bus_size_t size)
+{
+	struct bounce_zone *bz;
+	struct bounce_page *bpage, *bp1, *bp2;
+	int seg;
+
+	KASSERT(dmat->bounce_zone != NULL, ("no bounce zone in dma tag"));
+
+	bz = dmat->bounce_zone;
+	KASSERT(map->pagesneeded > 0, ("%s: map doesn't need any pages: %d",
+	    __func__, map->pagesneeded));
+	KASSERT(map->pagesreserved > 0, ("%s: map doesn't need any pages: %d",
+	    __func__, map->pagesreserved));
+	KASSERT(dmat->common.nsegments == 1, ("%s: tag nsegment != 1: %d",
+	    __func__, dmat->common.nsegments));
+
+	/*
+	 * Try to find enough contiguous pages to fullfill the the
+	 * nsegments == 1 constraint.
+	 */
+	mtx_lock(&bounce_lock);
+	bpage = STAILQ_FIRST(&bz->bounce_page_list);
+	if (bpage == NULL)
+		panic("%s: free page list is empty", __func__);
+	seg = 1;
+	bp2 = bpage;
+	while (seg < map->pagesneeded) {
+		bp1 = STAILQ_NEXT(bp2, links);
+		if (bp1 == NULL) {
+			/*
+			 * If we do not have enough contig. pages on the
+			 * bounce_page_list then we return -1 here enforcing
+			 * non-contiguency and _bus_dmamap_addseg will fail.
+			 * No need to do any more work here.
+			 */
+			mtx_unlock(&bounce_lock);
+			return (-1);
+		}
+		if ((bp2->busaddr + PAGE_SIZE) != bp1->busaddr) {
+			bpage = bp2 = bp1;
+			seg = 1;
+		} else {
+			bp2 = bp1;
+			seg++;
+		}
+	}
+
+	map->pagesneeded--;
+	map->pagesreserved--;
+	for (; seg > 0; seg--) {
+		bp2 = STAILQ_NEXT(bpage, links);
+		KASSERT(bp2 != NULL, ("%s: bpage %p bp2 %p seg %d (bp1 %p)\n",
+		    __func__, bpage, bp2, seg, bp1));
+		STAILQ_REMOVE(&bz->bounce_page_list, bpage, bounce_page, links);
+		STAILQ_INSERT_TAIL(&map->qbplist, bpage, links);
+		bz->reserved_bpages--;
+		bz->active_bpages++;
+		bpage = bp2;
+	}
+
+	bpage = STAILQ_FIRST(&map->qbplist);
+	KASSERT(bpage != NULL, ("%s:%d: bpage %p\n", __func__, __LINE__, bpage));
+	STAILQ_REMOVE_HEAD(&map->qbplist, links);
+	mtx_unlock(&bounce_lock);
+
+	if (dmat->common.flags & BUS_DMA_KEEP_PG_OFFSET) {
+		/* Page offset needs to be preserved. */
+		bpage->vaddr |= addr & PAGE_MASK;
+		bpage->busaddr |= addr & PAGE_MASK;
+	}
+	bpage->datavaddr = vaddr;
+	bpage->datapage = PHYS_TO_VM_PAGE(addr);
+	bpage->dataoffs = addr & PAGE_MASK;
+	bpage->datacount = size;
+	STAILQ_INSERT_TAIL(&(map->bpages), bpage, links);
+	return (bpage->busaddr);
+}
+
 static bus_addr_t
 add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map, vm_offset_t vaddr,
 		bus_addr_t addr, bus_size_t size)
@@ -1375,22 +1503,26 @@
 	KASSERT(dmat->bounce_zone != NULL, ("no bounce zone in dma tag"));
 
 	bz = dmat->bounce_zone;
-	if (map->pagesneeded == 0)
-		panic("add_bounce_page: map doesn't need any pages");
+	KASSERT(map->pagesneeded > 0, ("%s: map doesn't need any pages: %d",
+	    __func__, map->pagesneeded));
+	KASSERT(map->pagesreserved > 0, ("%s: map doesn't need any pages: %d",
+	    __func__, map->pagesreserved));
 	map->pagesneeded--;
-
-	if (map->pagesreserved == 0)
-		panic("add_bounce_page: map doesn't need any pages");
 	map->pagesreserved--;
 
 	mtx_lock(&bounce_lock);
-	bpage = STAILQ_FIRST(&bz->bounce_page_list);
-	if (bpage == NULL)
-		panic("add_bounce_page: free page list is empty");
+	if (!STAILQ_EMPTY(&map->qbplist)) {
+		bpage = STAILQ_FIRST(&map->qbplist);
+		STAILQ_REMOVE_HEAD(&map->qbplist, links);
 
-	STAILQ_REMOVE_HEAD(&bz->bounce_page_list, links);
-	bz->reserved_bpages--;
-	bz->active_bpages++;
+	} else {
+		bpage = STAILQ_FIRST(&bz->bounce_page_list);
+		if (bpage == NULL)
+			panic("add_bounce_page: free page list is empty");
+		STAILQ_REMOVE_HEAD(&bz->bounce_page_list, links);
+		bz->reserved_bpages--;
+		bz->active_bpages++;
+	}
 	mtx_unlock(&bounce_lock);
 
 	if (dmat->common.flags & BUS_DMA_KEEP_PG_OFFSET) {
@@ -1426,7 +1558,7 @@
 	}
 
 	mtx_lock(&bounce_lock);
-	STAILQ_INSERT_HEAD(&bz->bounce_page_list, bpage, links);
+	insert_bounce_page_sorted(bz, bpage);
 	bz->free_bpages++;
 	bz->active_bpages--;
 	if ((map = STAILQ_FIRST(&bounce_map_waitinglist)) != NULL) {