File-copy from v4.4.100
This is the result of 'cp' from a linux-stable tree with the 'v4.4.100'
tag checked out (commit 26d6298789e695c9f627ce49a7bbd2286405798a) on
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Please refer to that tree for all history prior to this point.
Change-Id: I8a9ee2aea93cd29c52c847d0ce33091a73ae6afe
diff --git a/Documentation/usb/chipidea.txt b/Documentation/usb/chipidea.txt
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+1. How to test OTG FSM(HNP and SRP)
+-----------------------------------
+To show how to demo OTG HNP and SRP functions via sys input files
+with 2 Freescale i.MX6Q sabre SD boards.
+
+1.1 How to enable OTG FSM in menuconfig
+---------------------------------------
+Select CONFIG_USB_OTG_FSM, rebuild kernel Image and modules.
+If you want to check some internal variables for otg fsm,
+select CONFIG_USB_CHIPIDEA_DEBUG, there are 2 files which
+can show otg fsm variables and some controller registers value:
+cat /sys/kernel/debug/ci_hdrc.0/otg
+cat /sys/kernel/debug/ci_hdrc.0/registers
+
+1.2 Test operations
+-------------------
+1) Power up 2 Freescale i.MX6Q sabre SD boards with gadget class driver loaded
+ (e.g. g_mass_storage).
+
+2) Connect 2 boards with usb cable with one end is micro A plug, the other end
+ is micro B plug.
+
+ The A-device(with micro A plug inserted) should enumrate B-device.
+
+3) Role switch
+ On B-device:
+ echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
+
+ if HNP polling is not supported, also need:
+ On A-device:
+ echo 0 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req
+
+ B-device should take host role and enumrate A-device.
+
+4) A-device switch back to host.
+ On B-device:
+ echo 0 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
+
+ A-device should switch back to host and enumrate B-device.
+
+5) Remove B-device(unplug micro B plug) and insert again in 10 seconds,
+ A-device should enumrate B-device again.
+
+6) Remove B-device(unplug micro B plug) and insert again after 10 seconds,
+ A-device should NOT enumrate B-device.
+
+ if A-device wants to use bus:
+ On A-device:
+ echo 0 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_drop
+ echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req
+
+ if B-device wants to use bus:
+ On B-device:
+ echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
+
+7) A-device power down the bus.
+ On A-device:
+ echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_drop
+
+ A-device should disconnect with B-device and power down the bus.
+
+8) B-device does data pulse for SRP.
+ On B-device:
+ echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
+
+ A-device should resume usb bus and enumrate B-device.
+
+1.3 Reference document
+----------------------
+"On-The-Go and Embedded Host Supplement to the USB Revision 2.0 Specification
+July 27, 2012 Revision 2.0 version 1.1a"
+
+2. How to enable USB as system wakeup source
+-----------------------------------
+Below is the example for how to enable USB as system wakeup source
+at imx6 platform.
+
+2.1 Enable core's wakeup
+echo enabled > /sys/bus/platform/devices/ci_hdrc.0/power/wakeup
+2.2 Enable glue layer's wakeup
+echo enabled > /sys/bus/platform/devices/2184000.usb/power/wakeup
+2.3 Enable PHY's wakeup (optional)
+echo enabled > /sys/bus/platform/devices/20c9000.usbphy/power/wakeup
+2.4 Enable roothub's wakeup
+echo enabled > /sys/bus/usb/devices/usb1/power/wakeup
+2.5 Enable related device's wakeup
+echo enabled > /sys/bus/usb/devices/1-1/power/wakeup
+
+If the system has only one usb port, and you want usb wakeup at this port, you
+can use below script to enable usb wakeup.
+for i in $(find /sys -name wakeup | grep usb);do echo enabled > $i;done;
+