Ensure that the DMA delay does not get rounded down to zero ticks when

a timeout value of a single tick is given. With FreeBSD-10 and newer
the current system time is used as a starting point, and the minimum
callout time of a single tick will be guaranteed. This patch mostly
affect the DMA delay timeouts, which are typically in the range from
0.125 to 2ms.

MFC after:	1 week

sys/dev/usb/usb_freebsd.h

@@ -50,6 +50,13 @@
 #define	USB_HAVE_FIXED_CONFIG 0
 #define	USB_HAVE_FIXED_PORT 0
 
+/* define zero ticks callout value */
+#if (__FreeBSD_version >= 1000029)
+#define	USB_CALLOUT_ZERO_TICKS 0
+#else
+#define	USB_CALLOUT_ZERO_TICKS 1
+#endif
+
 #define	USB_TD_GET_PROC(td) (td)->td_proc
 #define	USB_PROC_GET_GID(td) (td)->p_pgid
 

sys/dev/usb/usb_freebsd_loader.h

@@ -50,6 +50,8 @@
 #define	USB_HAVE_FIXED_CONFIG 0
 #define	USB_HAVE_FIXED_PORT 0
 
+#define	USB_CALLOUT_ZERO_TICKS 1
+
 #define	USB_TD_GET_PROC(td) (td)->td_proc
 #define	USB_PROC_GET_GID(td) (td)->p_pgid
 

sys/dev/usb/usb_transfer.c

@@ -2723,7 +2723,7 @@ usbd_transfer_timeout_ms(struct usb_xfer *xfer,
 
 	/* defer delay */
 	usb_callout_reset(&xfer->timeout_handle,
-	    USB_MS_TO_TICKS(ms), cb, xfer);
+	    USB_MS_TO_TICKS(ms) + USB_CALLOUT_ZERO_TICKS, cb, xfer);
 }
 
 /*------------------------------------------------------------------------*