--- linux-2.6.15-rc1/drivers/scsi/libata-scsi.c.orig	2005-11-11 20:43:36.000000000 -0500
+++ linux/drivers/scsi/libata-scsi.c	2005-11-12 18:45:43.000000000 -0500
@@ -2276,6 +2276,12 @@
 		tf->device = scsicmd[8];
 		tf->command = scsicmd[9];
 	}
+	/*
+	 * If slave is possible, enforce correct master/slave bit for this port:
+	 */
+	if (qc->ap->flags & ATA_FLAG_SLAVE_POSS)
+		tf->device = qc->dev->devno ?
+			tf->device | ATA_DEV1 : tf->device & ~ATA_DEV1;
 
 	/*
 	 * Filter SET_FEATURES - XFER MODE command -- otherwise,