Documentation: usb: ECM function testing

Summary of how to test ECM function of USB gadget.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/Documentation/usb/gadget-testing.txt b/Documentation/usb/gadget-testing.txt
index 2a448f812f0e..7df8785fc70d 100644
--- a/Documentation/usb/gadget-testing.txt
+++ b/Documentation/usb/gadget-testing.txt
@@ -2,6 +2,7 @@ This file summarizes information on basic testing of USB functions
 provided by gadgets.
 
 1. ACM function
+2. ECM function
 
 
 1. ACM function
@@ -32,3 +33,36 @@ then the other way round
 
 On the device: cat > /dev/ttyGS<Y>
 On the host: cat /dev/ttyACM<X>
+
+2. ECM function
+===============
+
+The function is provided by usb_f_ecm.ko module.
+
+Function-specific configfs interface
+------------------------------------
+
+The function name to use when creating the function directory is "ecm".
+The ECM function provides these attributes in its function directory:
+
+        ifname          - network device interface name associated with this
+                        function instance
+        qmult           - queue length multiplier for high and super speed
+        host_addr       - MAC address of host's end of this
+                        Ethernet over USB link
+        dev_addr        - MAC address of device's end of this
+                        Ethernet over USB link
+
+and after creating the functions/ecm.<instance name> they contain default
+values: qmult is 5, dev_addr and host_addr are randomly selected.
+Except for ifname they can be written to until the function is linked to a
+configuration. The ifname is read-only and contains the name of the interface
+which was assigned by the net core, e. g. usb0.
+
+Testing the ECM function
+------------------------
+
+Configure IP addresses of the device and the host. Then:
+
+On the device: ping <host's IP>
+On the host: ping <device's IP>