diff --git a/drivers/scsi/mac_scsi.c b/drivers/scsi/mac_scsi.c
index 2e511697fce3..d15d629f961c 100644
--- a/drivers/scsi/mac_scsi.c
+++ b/drivers/scsi/mac_scsi.c
@@ -286,13 +286,14 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
 	while (!NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 	                              BASR_DRQ | BASR_PHASE_MATCH,
 	                              BASR_DRQ | BASR_PHASE_MATCH, 0)) {
-		int bytes;
+		int bytes, chunk_bytes;
 
 		if (macintosh_config->ident == MAC_MODEL_IIFX)
 			write_ctrl_reg(hostdata, CTRL_HANDSHAKE_MODE |
 			                         CTRL_INTERRUPTS_ENABLE);
 
-		bytes = mac_pdma_recv(s, d, min(hostdata->pdma_residual, 512));
+		chunk_bytes = min(hostdata->pdma_residual, 512);
+		bytes = mac_pdma_recv(s, d, chunk_bytes);
 
 		if (bytes > 0) {
 			d += bytes;
@@ -302,23 +303,23 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
 		if (hostdata->pdma_residual == 0)
 			goto out;
 
-		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
-		                           BUS_AND_STATUS_REG, BASR_ACK,
-		                           BASR_ACK, 0) < 0)
-			scmd_printk(KERN_DEBUG, hostdata->connected,
-			            "%s: !REQ and !ACK\n", __func__);
 		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
 			goto out;
 
 		if (bytes == 0)
 			udelay(MAC_PDMA_DELAY);
 
-		if (bytes >= 0)
+		if (bytes > 0)
 			continue;
 
-		dsprintk(NDEBUG_PSEUDO_DMA, hostdata->host,
-		         "%s: bus error (%d/%d)\n", __func__, d - dst, len);
 		NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
+		dsprintk(NDEBUG_PSEUDO_DMA, hostdata->host,
+			 "%s: bus error [%d/%d] (%d/%d)\n",
+			 __func__, d - dst, len, bytes, chunk_bytes);
+
+		if (bytes == 0)
+			continue;
+
 		result = -1;
 		goto out;
 	}
@@ -345,13 +346,14 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 	while (!NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 	                              BASR_DRQ | BASR_PHASE_MATCH,
 	                              BASR_DRQ | BASR_PHASE_MATCH, 0)) {
-		int bytes;
+		int bytes, chunk_bytes;
 
 		if (macintosh_config->ident == MAC_MODEL_IIFX)
 			write_ctrl_reg(hostdata, CTRL_HANDSHAKE_MODE |
 			                         CTRL_INTERRUPTS_ENABLE);
 
-		bytes = mac_pdma_send(s, d, min(hostdata->pdma_residual, 512));
+		chunk_bytes = min(hostdata->pdma_residual, 512);
+		bytes = mac_pdma_send(s, d, chunk_bytes);
 
 		if (bytes > 0) {
 			s += bytes;
@@ -370,23 +372,23 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 			goto out;
 		}
 
-		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
-		                           BUS_AND_STATUS_REG, BASR_ACK,
-		                           BASR_ACK, 0) < 0)
-			scmd_printk(KERN_DEBUG, hostdata->connected,
-			            "%s: !REQ and !ACK\n", __func__);
 		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
 			goto out;
 
 		if (bytes == 0)
 			udelay(MAC_PDMA_DELAY);
 
-		if (bytes >= 0)
+		if (bytes > 0)
 			continue;
 
-		dsprintk(NDEBUG_PSEUDO_DMA, hostdata->host,
-		         "%s: bus error (%d/%d)\n", __func__, s - src, len);
 		NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
+		dsprintk(NDEBUG_PSEUDO_DMA, hostdata->host,
+			 "%s: bus error [%d/%d] (%d/%d)\n",
+			 __func__, s - src, len, bytes, chunk_bytes);
+
+		if (bytes == 0)
+			continue;
+
 		result = -1;
 		goto out;
 	}