make it possible to specify the USB bus

[usb-driver] / README

diff --git a/README b/README
index 5ce99d8823148324754cf8fef0a72073175fada0..f9b6cec9bb558abf9466d6f9f51b914710f53cc4 100644 (file)
--- a/README
+++ b/README
@@ -74,6 +74,14 @@ these steps:
 4. restart udev and re-plug the cable
 
 
+If you have multiple cables connected, you can specify the cable to use
+in the XILINX_USB_DEV environment-variable as "bus:device".
+These identifiers are available in the output of lsusb:
+Bus 001 Device 004: ID 03fd:0008 Xilinx, Inc.
+    ^^^        ^^^
+To use this cable, set the XILINX_USB_DEV variable to "001:004".
+
+
 Notes for the parallel cable
 ============================