Index: ahcisata_core.c
===================================================================
RCS file: /cvsroot/src/sys/dev/ic/ahcisata_core.c,v
retrieving revision 1.66
diff -u -p -r1.66 ahcisata_core.c
--- ahcisata_core.c	2 Nov 2018 21:27:30 -0000	1.66
+++ ahcisata_core.c	4 Nov 2018 08:32:42 -0000
@@ -791,13 +791,12 @@ ahci_do_reset_drive(struct ata_channel *
 	struct ahci_softc *sc = (struct ahci_softc *)chp->ch_atac;
 	struct ahci_cmd_tbl *cmd_tbl;
 	struct ahci_cmd_header *cmd_h;
-	int i;
+	int i, error = 0;
 	uint32_t sig;
 
 	KASSERT((AHCI_READ(sc, AHCI_P_CMD(chp->ch_channel)) & AHCI_P_CMD_CR) == 0);
 	ata_channel_lock_owned(chp);
 
-again:
 	/* clear port interrupt register */
 	AHCI_WRITE(sc, AHCI_P_IS(chp->ch_channel), 0xffffffff);
 	/* clear SErrors and start operations */
@@ -836,6 +835,7 @@ again:
 		    "for drive %d\n", AHCINAME(sc), chp->ch_channel, drive);
 		if (sigp)
 			*sigp = 0xffffffff;
+		error = EBUSY;
 		goto end;
 	default:
 		break;
@@ -850,21 +850,11 @@ again:
 	switch(ahci_exec_fis(chp, 310, flags, c_slot)) {
 	case ERR_DF:
 	case TIMEOUT:
-		if ((sc->sc_ahci_quirks & AHCI_QUIRK_BADPMPRESET) != 0 &&
-		    drive == PMP_PORT_CTL) {
-			/*
-			 * some controllers fails to reset when
-			 * targeting a PMP but a single drive is attached.
-			 * try again with port 0
-			 */
-			drive = 0;
-			ahci_channel_stop(sc, chp, flags);
-			goto again;
-		}
 		aprint_error("%s channel %d: clearing WDCTL_RST failed "
 		    "for drive %d\n", AHCINAME(sc), chp->ch_channel, drive);
 		if (sigp)
 			*sigp = 0xffffffff;
+		error = EBUSY;
 		goto end;
 	default:
 		break;
@@ -904,7 +894,7 @@ end:
 	AHCI_WRITE(sc, AHCI_P_IS(chp->ch_channel), 0xffffffff);
 	ahci_channel_start(sc, chp, flags,
 	    (sc->sc_ahci_cap & AHCI_CAP_CLO) ? 1 : 0);
-	return 0;
+	return error;
 }
 
 static void
@@ -972,6 +962,7 @@ ahci_probe_drive(struct ata_channel *chp
 	struct ahci_channel *achp = (struct ahci_channel *)chp;
 	uint32_t sig;
 	uint8_t c_slot;
+	int error;
 
 	ata_channel_lock(chp);
 
@@ -994,8 +985,19 @@ ahci_probe_drive(struct ata_channel *chp
 	case SStatus_DET_DEV:
 		ata_delay(chp, 500, "ahcidv", AT_WAIT);
 		if (sc->sc_ahci_cap & AHCI_CAP_SPM) {
-			ahci_do_reset_drive(chp, PMP_PORT_CTL, AT_WAIT, &sig,
-			    c_slot);
+			error = ahci_do_reset_drive(chp, PMP_PORT_CTL, AT_WAIT,
+			    &sig, c_slot);
+
+			/* If probe for PMP failed, just fallback to drive 0 */
+			if (error) {
+				aprint_error_dev(sc->sc_atac.atac_dev,
+				    "drive %d reset failing, disabling PMP\n",
+				    PMP_PORT_CTL);
+
+				sc->sc_ahci_cap &= ~AHCI_CAP_SPM;
+				ahci_do_reset_drive(chp, 0, AT_WAIT, &sig,
+				    c_slot);
+			}
 		} else {
 			ahci_do_reset_drive(chp, 0, AT_WAIT, &sig, c_slot);
 		}