diff --git a/sys/bus/firewire/fwohci.c b/sys/bus/firewire/fwohci.c
--- a/sys/bus/firewire/fwohci.c
+++ b/sys/bus/firewire/fwohci.c
@@ -1861,10 +1861,10 @@
 		OWRITE(sc, FWOHCI_INTMASK,  OHCI_INT_PHY_BUS_R);
 		/* Allow async. request to us */
 		OWRITE(sc, OHCI_AREQHI, 1 << 31);
-		/* XXX insecure ?? */
-		OWRITE(sc, OHCI_PREQHI, 0x7fffffff);
-		OWRITE(sc, OHCI_PREQLO, 0xffffffff);
-		OWRITE(sc, OHCI_PREQUPPER, 0x10000);
+		/* DF-1009: do not enable FireWire physical-request DMA by default */
+		OWRITE(sc, OHCI_PREQHI, 0);
+		OWRITE(sc, OHCI_PREQLO, 0);
+		OWRITE(sc, OHCI_PREQUPPER, 0);
 		/* Set ATRetries register */
 		OWRITE(sc, OHCI_ATRETRY, 1<<(13+16) | 0xfff);
 /*