Index: if_iwn.c
===================================================================
--- if_iwn.c	(revision 309541)
+++ if_iwn.c	(working copy)
@@ -1910,6 +1910,9 @@
 			goto fail;
 		}
 
+		bus_dmamap_sync(ring->data_dmat, data->map,
+		    BUS_DMASYNC_PREREAD);
+
 		/* Set physical address of RX buffer (256-byte aligned). */
 		ring->desc[i] = htole32(paddr >> 8);
 	}
@@ -3042,12 +3045,15 @@
 		}
 		/* Physical address may have changed. */
 		ring->desc[ring->cur] = htole32(paddr >> 8);
-		bus_dmamap_sync(ring->data_dmat, ring->desc_dma.map,
+		bus_dmamap_sync(ring->desc_dma.tag, ring->desc_dma.map,
 		    BUS_DMASYNC_PREWRITE);
 		counter_u64_add(ic->ic_ierrors, 1);
 		return;
 	}
 
+	bus_dmamap_sync(ring->data_dmat, data->map,
+	    BUS_DMASYNC_PREREAD);
+
 	m = data->m;
 	data->m = m1;
 	/* Update RX descriptor. */