tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 in menuconfig
7---------------------------------------
8Select CONFIG_USB_OTG_FSM, rebuild kernel Image and modules.
9If you want to check some internal variables for otg fsm,
10select CONFIG_USB_CHIPIDEA_DEBUG, there are 2 files which
11can 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
14
151.2 Test operations
16-------------------
171) Power up 2 Freescale i.MX6Q sabre SD boards with gadget class driver loaded
18 (e.g. g_mass_storage).
19
202) Connect 2 boards with usb cable with one end is micro A plug, the other end
21 is micro B plug.
22
23 The A-device(with micro A plug inserted) should enumrate B-device.
24
253) Role switch
26 On B-device:
27 echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
28
29 if HNP polling is not supported, also need:
30 On A-device:
31 echo 0 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req
32
33 B-device should take host role and enumrate A-device.
34
354) A-device switch back to host.
36 On B-device:
37 echo 0 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
38
39 A-device should switch back to host and enumrate B-device.
40
415) Remove B-device(unplug micro B plug) and insert again in 10 seconds,
42 A-device should enumrate B-device again.
43
446) Remove B-device(unplug micro B plug) and insert again after 10 seconds,
45 A-device should NOT enumrate B-device.
46
47 if A-device wants to use bus:
48 On A-device:
49 echo 0 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_drop
50 echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req
51
52 if B-device wants to use bus:
53 On B-device:
54 echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
55
567) A-device power down the bus.
57 On A-device:
58 echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_drop
59
60 A-device should disconnect with B-device and power down the bus.
61
628) B-device does data pulse for SRP.
63 On B-device:
64 echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
65
66 A-device should resume usb bus and enumrate B-device.
67
681.3 Reference document
69----------------------
70"On-The-Go and Embedded Host Supplement to the USB Revision 2.0 Specification
71July 27, 2012 Revision 2.0 version 1.1a"
72
732. How to enable USB as system wakeup source
74-----------------------------------
75Below is the example for how to enable USB as system wakeup source
76at imx6 platform.
77
782.1 Enable core's wakeup
79echo enabled > /sys/bus/platform/devices/ci_hdrc.0/power/wakeup
802.2 Enable glue layer's wakeup
81echo enabled > /sys/bus/platform/devices/2184000.usb/power/wakeup
822.3 Enable PHY's wakeup (optional)
83echo enabled > /sys/bus/platform/devices/20c9000.usbphy/power/wakeup
842.4 Enable roothub's wakeup
85echo enabled > /sys/bus/usb/devices/usb1/power/wakeup
862.5 Enable related device's wakeup
87echo enabled > /sys/bus/usb/devices/1-1/power/wakeup
88
89If the system has only one usb port, and you want usb wakeup at this port, you
90can use below script to enable usb wakeup.
91for i in $(find /sys -name wakeup | grep usb);do echo enabled > $i;done;
92