--- linux-2.6.12/drivers/scsi/aic7xxx/aic79xx_osm.c.jejb	2005-07-25 09:21:41.000000000 +0200
+++ linux-2.6.12/drivers/scsi/aic7xxx/aic79xx_osm.c	2005-07-25 09:22:37.000000000 +0200
@@ -2343,6 +2343,7 @@ static void ahd_linux_set_period(struct 
 				      shost->this_id, starget->id, &tstate);
 	struct ahd_devinfo devinfo;
 	unsigned int ppr_options = tinfo->goal.ppr_options;
+	unsigned int dt;
 	unsigned long flags;
 	unsigned long offset = tinfo->goal.offset;
 
@@ -2357,6 +2358,8 @@ static void ahd_linux_set_period(struct 
 			ppr_options |= MSG_EXT_PPR_IU_REQ;
 	}
 
+	dt = ppr_options & MSG_EXT_PPR_DT_REQ;
+
 	ahd_compile_devinfo(&devinfo, shost->this_id, starget->id, 0,
 			    starget->channel + 'A', ROLE_INITIATOR);
 
@@ -2366,7 +2369,8 @@ static void ahd_linux_set_period(struct 
 			ppr_options &= MSG_EXT_PPR_QAS_REQ;
 	}
 
-	ahd_find_syncrate(ahd, &period, &ppr_options, AHD_SYNCRATE_MAX);
+	ahd_find_syncrate(ahd, &period, &ppr_options,
+			  dt ? AHD_SYNCRATE_MAX : AHD_SYNCRATE_ULTRA2);
 	ahd_lock(ahd, &flags);
 	ahd_set_syncrate(ahd, &devinfo, period, offset,
 			 ppr_options, AHD_TRANS_GOAL, FALSE);
@@ -2385,6 +2389,7 @@ static void ahd_linux_set_offset(struct 
 	struct ahd_devinfo devinfo;
 	unsigned int ppr_options = 0;
 	unsigned int period = 0;
+	unsigned int dt = ppr_options & MSG_EXT_PPR_DT_REQ;
 	unsigned long flags;
 
 	ahd_compile_devinfo(&devinfo, shost->this_id, starget->id, 0,
@@ -2392,7 +2397,8 @@ static void ahd_linux_set_offset(struct 
 	if (offset != 0) {
 		period = tinfo->goal.period;
 		ppr_options = tinfo->goal.ppr_options;
-		ahd_find_syncrate(ahd, &period, &ppr_options, AHD_SYNCRATE_MAX);
+		ahd_find_syncrate(ahd, &period, &ppr_options, 
+				  dt ? AHD_SYNCRATE_MAX : AHD_SYNCRATE_ULTRA2);
 	}
 	ahd_lock(ahd, &flags);
 	ahd_set_syncrate(ahd, &devinfo, period, offset, ppr_options,
@@ -2419,9 +2425,13 @@ static void ahd_linux_set_dt(struct scsi
 		ppr_options |= MSG_EXT_PPR_DT_REQ;
 		if (period > 9)
 			period = 9; /* at least 12.5ns for DT */
-	} else if (period <= 9)
-		period = 10; /* If resetting DT, period must be >= 25ns */
-
+	} else {
+		if (period <= 9)
+			period = 10; /* If resetting DT, period must be >= 25ns */
+		/* QAS and IU are invalid without DT set */
+		ppr_options &= ~MSG_EXT_PPR_IU_REQ;
+		ppr_options &= ~MSG_EXT_PPR_QAS_REQ;
+	}
 	ahd_compile_devinfo(&devinfo, shost->this_id, starget->id, 0,
 			    starget->channel + 'A', ROLE_INITIATOR);
 	ahd_find_syncrate(ahd, &period, &ppr_options,
@@ -2445,11 +2455,17 @@ static void ahd_linux_set_qas(struct scs
 	unsigned int ppr_options = tinfo->goal.ppr_options
 		& ~MSG_EXT_PPR_QAS_REQ;
 	unsigned int period = tinfo->goal.period;
-	unsigned int dt = ppr_options & MSG_EXT_PPR_DT_REQ;
+	unsigned int dt;
 	unsigned long flags;
 
-	if (qas)
-		ppr_options |= MSG_EXT_PPR_QAS_REQ;
+	if (qas) {
+		/* QAS requires IU and DT to be set */
+		ppr_options |= MSG_EXT_PPR_QAS_REQ; 
+		ppr_options |= MSG_EXT_PPR_IU_REQ;
+		ppr_options |= MSG_EXT_PPR_DT_REQ;
+	}
+
+	dt = ppr_options & MSG_EXT_PPR_DT_REQ;
 
 	ahd_compile_devinfo(&devinfo, shost->this_id, starget->id, 0,
 			    starget->channel + 'A', ROLE_INITIATOR);
@@ -2474,11 +2490,17 @@ static void ahd_linux_set_iu(struct scsi
 	unsigned int ppr_options = tinfo->goal.ppr_options
 		& ~MSG_EXT_PPR_IU_REQ;
 	unsigned int period = tinfo->goal.period;
-	unsigned int dt = ppr_options & MSG_EXT_PPR_DT_REQ;
+	unsigned int dt;
 	unsigned long flags;
 
-	if (iu)
+	if (iu) {
 		ppr_options |= MSG_EXT_PPR_IU_REQ;
+		ppr_options |= MSG_EXT_PPR_DT_REQ; /* IU requires DT */
+	} else {
+		ppr_options &= ~MSG_EXT_PPR_QAS_REQ; /* No QAS without IU */
+	}
+
+	dt = ppr_options & MSG_EXT_PPR_DT_REQ;
 
 	ahd_compile_devinfo(&devinfo, shost->this_id, starget->id, 0,
 			    starget->channel + 'A', ROLE_INITIATOR);