diff --git a/sys/cam/cam_ccb.h b/sys/cam/cam_ccb.h
index 32245225ddb8..2184465bda95 100644
--- a/sys/cam/cam_ccb.h
+++ b/sys/cam/cam_ccb.h
@@ -58,6 +58,10 @@ typedef enum {
 	CAM_CDB_POINTER		= 0x00000001,/* The CDB field is a pointer    */
 	CAM_QUEUE_ENABLE	= 0x00000002,/* SIM queue actions are enabled */
 	CAM_CDB_LINKED		= 0x00000004,/* CCB contains a linked CDB     */
+	CAM_NEGOTIATE		= 0x00000008,/*
+					      * Perform transport negotiation
+					      * with this command.
+					      */
 	CAM_SCATTER_VALID	= 0x00000010,/* Scatter/gather list is valid  */
 	CAM_DIS_AUTOSENSE	= 0x00000020,/* Disable autosense feature     */
 	CAM_DIR_RESV		= 0x00000000,/* Data direction (00:reserved)  */
diff --git a/sys/cam/cam_xpt.c b/sys/cam/cam_xpt.c
index 72f971cca6af..4e2a6b461e9c 100644
--- a/sys/cam/cam_xpt.c
+++ b/sys/cam/cam_xpt.c
@@ -5786,6 +5786,15 @@ xpt_set_transfer_settings(struct ccb_trans_settings *cts, struct cam_ed *device,
 			cts->sync_offset = 0;
 		}
 
+		/*
+		 * Don't allow DT transmission rates if the
+		 * device does not support it.
+		 */
+		if ((device->flags & CAM_DEV_INQUIRY_DATA_VALID) != 0
+		 && (inq_data->spi3data & SID_SPI_CLOCK_DT) == 0
+		 && cts->sync_period <= 0x9)
+			cts->sync_period = 0xa;
+
 		switch (cts->bus_width) {
 		case MSG_EXT_WDTR_BUS_32_BIT:
 			if (((device->flags & CAM_DEV_INQUIRY_DATA_VALID) == 0