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Based on kernel version 4.8. Page generated on 2016-10-06 23:19 EST.

1	1. How to test OTG FSM(HNP and SRP)
2	-----------------------------------
3	To show how to demo OTG HNP and SRP functions via sys input files
4	with 2 Freescale i.MX6Q sabre SD boards.
5	
6	1.1 How to enable OTG FSM
7	---------------------------------------
8	1.1.1 Select CONFIG_USB_OTG_FSM in menuconfig, rebuild kernel
9	Image and modules. If you want to check some internal
10	variables for otg fsm, mount debugfs, there are 2 files
11	which can show otg fsm variables and some controller registers value:
12	cat /sys/kernel/debug/ci_hdrc.0/otg
13	cat /sys/kernel/debug/ci_hdrc.0/registers
14	1.1.2 Add below entries in your dts file for your controller node
15		otg-rev = <0x0200>;
16		adp-disable;
17	
18	1.2 Test operations
19	-------------------
20	1) Power up 2 Freescale i.MX6Q sabre SD boards with gadget class driver loaded
21	   (e.g. g_mass_storage).
22	
23	2) 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 enumrate B-device.
27	
28	3) 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 enumrate A-device.
33	
34	4) 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 enumrate B-device.
44	
45	5) Remove B-device(unplug micro B plug) and insert again in 10 seconds,
46	   A-device should enumrate B-device again.
47	
48	6) Remove B-device(unplug micro B plug) and insert again after 10 seconds,
49	   A-device should NOT enumrate 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	
60	7) 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	
66	8) 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 enumrate B-device.
71	
72	1.3 Reference document
73	----------------------
74	"On-The-Go and Embedded Host Supplement to the USB Revision 2.0 Specification
75	July 27, 2012 Revision 2.0 version 1.1a"
76	
77	2. How to enable USB as system wakeup source
78	-----------------------------------
79	Below is the example for how to enable USB as system wakeup source
80	at imx6 platform.
81	
82	2.1 Enable core's wakeup
83	echo enabled > /sys/bus/platform/devices/ci_hdrc.0/power/wakeup
84	2.2 Enable glue layer's wakeup
85	echo enabled > /sys/bus/platform/devices/2184000.usb/power/wakeup
86	2.3 Enable PHY's wakeup (optional)
87	echo enabled > /sys/bus/platform/devices/20c9000.usbphy/power/wakeup
88	2.4 Enable roothub's wakeup
89	echo enabled > /sys/bus/usb/devices/usb1/power/wakeup
90	2.5 Enable related device's wakeup
91	echo enabled > /sys/bus/usb/devices/1-1/power/wakeup
92	
93	If the system has only one usb port, and you want usb wakeup at this port, you
94	can use below script to enable usb wakeup.
95	for i in $(find /sys -name wakeup | grep usb);do echo enabled > $i;done;
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