11. How to test OTG FSM(HNP and SRP)
2-----------------------------------
3To show how to demo OTG HNP and SRP functions via sys input files
4with 2 Freescale i.MX6Q sabre SD boards.
5
61.1 How to enable OTG FSM
7---------------------------------------
81.1.1 Select CONFIG_USB_OTG_FSM in menuconfig, rebuild kernel
9Image and modules. If you want to check some internal
10variables for otg fsm, mount debugfs, there are 2 files
11which can show otg fsm variables and some controller registers value:
12cat /sys/kernel/debug/ci_hdrc.0/otg
13cat /sys/kernel/debug/ci_hdrc.0/registers
141.1.2 Add below entries in your dts file for your controller node
15	otg-rev = <0x0200>;
16	adp-disable;
17
181.2 Test operations
19-------------------
201) Power up 2 Freescale i.MX6Q sabre SD boards with gadget class driver loaded
21   (e.g. g_mass_storage).
22
232) Connect 2 boards with usb cable with one end is micro A plug, the other end
24   is micro B plug.
25
26   The A-device(with micro A plug inserted) should enumerate B-device.
27
283) Role switch
29   On B-device:
30   echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
31
32   B-device should take host role and enumerate A-device.
33
344) A-device switch back to host.
35   On B-device:
36   echo 0 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
37
38   or, by introducing HNP polling, B-Host can know when A-peripheral wish
39   to be host role, so this role switch also can be trigged in A-peripheral
40   side by answering the polling from B-Host, this can be done on A-device:
41   echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req
42
43   A-device should switch back to host and enumerate B-device.
44
455) Remove B-device(unplug micro B plug) and insert again in 10 seconds,
46   A-device should enumerate B-device again.
47
486) Remove B-device(unplug micro B plug) and insert again after 10 seconds,
49   A-device should NOT enumerate B-device.
50
51   if A-device wants to use bus:
52   On A-device:
53   echo 0 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_drop
54   echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req
55
56   if B-device wants to use bus:
57   On B-device:
58   echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
59
607) A-device power down the bus.
61   On A-device:
62   echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_drop
63
64   A-device should disconnect with B-device and power down the bus.
65
668) B-device does data pulse for SRP.
67   On B-device:
68   echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
69
70   A-device should resume usb bus and enumerate B-device.
71
721.3 Reference document
73----------------------
74"On-The-Go and Embedded Host Supplement to the USB Revision 2.0 Specification
75July 27, 2012 Revision 2.0 version 1.1a"
76
772. How to enable USB as system wakeup source
78-----------------------------------
79Below is the example for how to enable USB as system wakeup source
80at imx6 platform.
81
822.1 Enable core's wakeup
83echo enabled > /sys/bus/platform/devices/ci_hdrc.0/power/wakeup
842.2 Enable glue layer's wakeup
85echo enabled > /sys/bus/platform/devices/2184000.usb/power/wakeup
862.3 Enable PHY's wakeup (optional)
87echo enabled > /sys/bus/platform/devices/20c9000.usbphy/power/wakeup
882.4 Enable roothub's wakeup
89echo enabled > /sys/bus/usb/devices/usb1/power/wakeup
902.5 Enable related device's wakeup
91echo enabled > /sys/bus/usb/devices/1-1/power/wakeup
92
93If the system has only one usb port, and you want usb wakeup at this port, you
94can use below script to enable usb wakeup.
95for i in $(find /sys -name wakeup | grep usb);do echo enabled > $i;done;
96
97