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kernel/linux-imx6_3.14.28/Documentation/usb/chipidea.txt 3.35 KB
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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
  
     B-device should take host role and enumrate A-device.
  
  4) A-device switch back to host.
     On A-device:
     echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req
  
     or, 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"
  
  1.4 OTG compliance test
  ----------------------
  Only below 3 popular gadget drivers are declared to be USB OTG and EH 2.0
  compliant(with otg descriptor comply with USB OTG and EH 2.0 as a peripheral):
  - mass storage
  - ether
  - serial
  
  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;