In the interrupt handler, if there is a DMA transfer in progress, do

not busy wait for the transfer to complete at the very beginning, as
this interrupt could be unrelated to the transfer; busywaiting could
cause the scsi command timeout to be triggered, and the code would not
recover correctly.

Instead, make the DMA check simply return, leaving the "busy" flag set;
and perform the usual interrupt handler duties, except for the phase
change.

test&ok millert@

2 files changed, 28 insertions, 24 deletions

diff --git a/sys/arch/hp300/dev/mb89352.c b/sys/arch/hp300/dev/mb89352.c
index 3019c3bb91b..dcda7432de3 100644
--- a/sys/arch/hp300/dev/mb89352.c
+++ b/sys/arch/hp300/dev/mb89352.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mb89352.c,v 1.6 2004/08/21 18:00:26 miod Exp $	*/
+/*	$OpenBSD: mb89352.c,v 1.7 2004/08/30 17:01:43 miod Exp $	*/
 /*	$NetBSD: mb89352.c,v 1.5 2000/03/23 07:01:31 thorpej Exp $	*/
 /*	NecBSD: mb89352.c,v 1.4 1998/03/14 07:31:20 kmatsuda Exp	*/
 
@@ -1485,26 +1485,29 @@ spc_process_intr(void *arg, u_char ints)
 
 	SPC_TRACE(("spc_process_intr  "));
 
-	if (sc->sc_dma_done != NULL &&
-	    sc->sc_state == SPC_CONNECTED &&
-	    (sc->sc_flags & SPC_DOINGDMA) != 0 &&
-	    (sc->sc_phase == PH_DATAOUT || sc->sc_phase == PH_DATAIN)) {
-		(*sc->sc_dma_done)(sc);
-	}
-
 	goto start;
 
 loop:
 	/*
 	 * Loop until transfer completion.
 	 */
-	/*
-	 * First check for abnormal conditions, such as reset.
-	 */
 	ints = spc_read(INTS);
 start:
 	SPC_MISC(("ints = 0x%x  ", ints));
 
+	/*
+	 * Check for the end of a DMA operation before doing anything else...
+	 */
+	if (sc->sc_dma_done != NULL &&
+	    sc->sc_state == SPC_CONNECTED &&
+	    (sc->sc_flags & SPC_DOINGDMA) != 0 &&
+	    (sc->sc_phase == PH_DATAOUT || sc->sc_phase == PH_DATAIN)) {
+		(*sc->sc_dma_done)(sc);
+	}
+
+	/*
+	 * Then check for abnormal conditions, such as reset.
+	 */
 	if ((ints & INTS_RST) != 0) {
 		printf("%s: SCSI bus reset\n", sc->sc_dev.dv_xname);
 		goto reset;
@@ -1734,6 +1737,16 @@ start:
 	    sc->sc_state != SPC_CONNECTED)
 		goto out;
 
+	/*
+	 * Do not change phase (yet) if we have a pending DMA operation.
+	 */
+	if (sc->sc_dma_done != NULL &&
+	    sc->sc_state == SPC_CONNECTED &&
+	    (sc->sc_flags & SPC_DOINGDMA) != 0 &&
+	    (sc->sc_phase == PH_DATAOUT || sc->sc_phase == PH_DATAIN)) {
+		goto out;
+	}
+
 dophase:
 #if 0
 	if ((spc_read(PSNS) & PSNS_REQ) == 0) {
diff --git a/sys/arch/hp300/dev/spc.c b/sys/arch/hp300/dev/spc.c
index 7fa89855b19..83bfc354845 100644
--- a/sys/arch/hp300/dev/spc.c
+++ b/sys/arch/hp300/dev/spc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: spc.c,v 1.7 2004/08/25 21:00:37 miod Exp $ */
+/* $OpenBSD: spc.c,v 1.8 2004/08/30 17:01:43 miod Exp $ */
 /* $NetBSD: spc.c,v 1.2 2003/11/17 14:37:59 tsutsui Exp $ */
 
 /*
@@ -246,18 +246,9 @@ spc_dio_dmadone(struct spc_softc *sc)
 	int resid, trans;
 	u_int8_t cmd;
 
-	/* wait DMA complete */
-	if ((spc_read(SSTS) & SSTS_BUSY) != 0) {
-		int timeout = 1000; /* XXX how long? */
-		while ((spc_read(SSTS) & SSTS_BUSY) != 0) {
-			if (--timeout < 0) {
-				printf("%s: DMA complete timeout\n",
-				    sc->sc_dev.dv_xname);
-				timeout = 1000;
-			}
-			DELAY(1);
-		}
-	}
+	/* Check if the DMA operation is finished. */
+	if ((spc_read(SSTS) & SSTS_BUSY) != 0)
+		return;
 
 	sc->sc_flags &= ~SPC_DOINGDMA;
 	if ((dsc->sc_dflags & SCSI_HAVEDMA) != 0) {