scsi: mac_scsi: Treat Last Byte Sent time-out as failure

A system bus error during a PDMA send operation can result in bytes being
lost. Theoretically that could cause the target to remain in DATA OUT phase
and the initiator (expecting a phase change) would time-out waiting for the
Last Byte Sent flag. Should that happen, fail the transfer so the core
driver will stop using PDMA with this target.

Cc: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Stan Johnson <userm57@yahoo.com>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/mac_scsi.c

@@ -360,9 +360,12 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 		if (hostdata->pdma_residual == 0) {
 			if (NCR5380_poll_politely(hostdata, TARGET_COMMAND_REG,
 			                          TCR_LAST_BYTE_SENT,
-			                          TCR_LAST_BYTE_SENT, HZ / 64) < 0)
+			                          TCR_LAST_BYTE_SENT,
+			                          HZ / 64) < 0) {
 				scmd_printk(KERN_ERR, hostdata->connected,
 				            "%s: Last Byte Sent timeout\n", __func__);
+				result = -1;
+			}
 			goto out;
 		}