Index: sys/arch/arm/broadcom/bcm2835_emmc.c
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/broadcom/bcm2835_emmc.c,v
retrieving revision 1.9.4.2
diff -u -p -r1.9.4.2 bcm2835_emmc.c
--- sys/arch/arm/broadcom/bcm2835_emmc.c	5 Oct 2014 20:00:54 -0000	1.9.4.2
+++ sys/arch/arm/broadcom/bcm2835_emmc.c	25 Nov 2014 13:59:54 -0000
@@ -248,9 +248,21 @@ bcmemmc_xfer_data_dma(struct sdhc_softc 
 	for (seg = 0; seg < cmd->c_dmamap->dm_nsegs; seg++) {
 		sc->sc_cblk[seg].cb_ti =
 		    __SHIFTIN(11, DMAC_TI_PERMAP); /* e.MMC */
+		sc->sc_cblk[seg].cb_txfr_len =
+		    cmd->c_dmamap->dm_segs[seg].ds_len;
+		/*
+		 * All transfers are assumed to be multiples of 32-bits.
+		 */
+		KASSERTMSG((sc->sc_cblk[seg].cb_txfr_len & 0x3) == 0,
+		    "seg %zu len %d", seg, sc->sc_cblk[seg].cb_txfr_len);
 		if (ISSET(cmd->c_flags, SCF_CMD_READ)) {
 			sc->sc_cblk[seg].cb_ti |= DMAC_TI_DEST_INC;
-			sc->sc_cblk[seg].cb_ti |= DMAC_TI_DEST_WIDTH;
+			/*
+			 * Use 128-bit mode if transfer is a multiple of
+			 * 16-bytes.
+			 */
+			if ((sc->sc_cblk[seg].cb_txfr_len & 0xf) == 0)
+				sc->sc_cblk[seg].cb_ti |= DMAC_TI_DEST_WIDTH;
 			sc->sc_cblk[seg].cb_ti |= DMAC_TI_SRC_DREQ;
 			sc->sc_cblk[seg].cb_source_ad =
 			    BCM2835_PERIPHERALS_TO_BUS(sc->sc_physaddr +
@@ -259,7 +271,12 @@ bcmemmc_xfer_data_dma(struct sdhc_softc 
 			    cmd->c_dmamap->dm_segs[seg].ds_addr;
 		} else {
 			sc->sc_cblk[seg].cb_ti |= DMAC_TI_SRC_INC;
-			sc->sc_cblk[seg].cb_ti |= DMAC_TI_SRC_WIDTH;
+			/*
+			 * Use 128-bit mode if transfer is a multiple of
+			 * 16-bytes.
+			 */
+			if ((sc->sc_cblk[seg].cb_txfr_len & 0xf) == 0)
+				sc->sc_cblk[seg].cb_ti |= DMAC_TI_SRC_WIDTH;
 			sc->sc_cblk[seg].cb_ti |= DMAC_TI_DEST_DREQ;
 			sc->sc_cblk[seg].cb_source_ad =
 			    cmd->c_dmamap->dm_segs[seg].ds_addr;
@@ -267,8 +284,6 @@ bcmemmc_xfer_data_dma(struct sdhc_softc 
 			    BCM2835_PERIPHERALS_TO_BUS(sc->sc_physaddr +
 			    SDHC_DATA);
 		}
-		sc->sc_cblk[seg].cb_txfr_len =
-		    cmd->c_dmamap->dm_segs[seg].ds_len;
 		sc->sc_cblk[seg].cb_stride = 0;
 		if (seg == cmd->c_dmamap->dm_nsegs - 1) {
 			sc->sc_cblk[seg].cb_ti |= DMAC_TI_WAIT_RESP;