diff --git a/drivers/scsi/mac_scsi.c b/drivers/scsi/mac_scsi.c
index a590089b9397..5648d30c7376 100644
--- a/drivers/scsi/mac_scsi.c
+++ b/drivers/scsi/mac_scsi.c
@@ -54,7 +54,7 @@ static int setup_cmd_per_lun = -1;
 module_param(setup_cmd_per_lun, int, 0);
 static int setup_sg_tablesize = -1;
 module_param(setup_sg_tablesize, int, 0);
-static int setup_use_pdma = -1;
+static int setup_use_pdma = 512;
 module_param(setup_use_pdma, int, 0);
 static int setup_hostid = -1;
 module_param(setup_hostid, int, 0);
@@ -325,7 +325,7 @@ static int macscsi_dma_xfer_len(struct Scsi_Host *instance,
 	struct NCR5380_hostdata *hostdata = shost_priv(instance);
 
 	if (hostdata->flags & FLAG_NO_PSEUDO_DMA ||
-	    cmd->SCp.this_residual < 16)
+	    cmd->SCp.this_residual < setup_use_pdma)
 		return 0;
 
 	return cmd->SCp.this_residual;