Index: sys/dev/ahci/ahci.c
===================================================================
--- sys/dev/ahci/ahci.c
+++ sys/dev/ahci/ahci.c
@@ -483,6 +483,10 @@
 	/* AHCI declares level triggered IS. */
 	if (!(ctlr->quirks & AHCI_Q_EDGEIS))
 		ATA_OUTL(ctlr->r_mem, AHCI_IS, is);
+#ifdef __arm__
+	/* Readback ensures that AHCI_IS is already updated in HW */
+	ATA_INL(ctlr->r_mem, AHCI_IS);
+#endif
 }
 
 /*
@@ -501,6 +505,10 @@
 	    ctlr->interrupt[unit].function(arg);
 	/* AHCI declares level triggered IS. */
 	ATA_OUTL(ctlr->r_mem, AHCI_IS, 1 << unit);
+#ifdef __arm__
+	/* Readback ensures that AHCI_IS is already updated in HW */
+	ATA_INL(ctlr->r_mem, AHCI_IS);
+#endif
 }
 
 static void
@@ -516,6 +524,10 @@
 	ATA_OUTL(ctlr->r_mem, AHCI_IS, 1 << unit);
 	if ((arg = ctlr->interrupt[unit].argument))
 		ctlr->interrupt[unit].function(arg);
+#ifdef __arm__
+	/* Readback ensures that AHCI_IS is already updated in HW */
+	ATA_INL(ctlr->r_mem, AHCI_IS);
+#endif
 }
 
 struct resource *
@@ -1606,10 +1618,15 @@
 		if ((ch->quirks & AHCI_Q_NOBSYRES) == 0 &&
 		    (ch->quirks & AHCI_Q_ATI_PMP_BUG) == 0 &&
 		    softreset == 2 && et == AHCI_ERR_NONE) {
-			while ((val = fis[2]) & ATA_S_BUSY) {
-				DELAY(10);
-				if (count++ >= timeout)
+			for ( ; count < timeout; count++) {
+				bus_dmamap_sync(ch->dma.rfis_tag,
+				    ch->dma.rfis_map, BUS_DMASYNC_POSTREAD);
+				val = fis[2];
+				bus_dmamap_sync(ch->dma.rfis_tag,
+				    ch->dma.rfis_map, BUS_DMASYNC_PREREAD);
+				if ((val & ATA_S_BUSY) == 0)
 					break;
+				DELAY(10);
 			}
 		}