Documentation/usb/chipidea.rst

   1 ==============================================
   2 ChipIdea Highspeed Dual Role Controller Driver
   3 ==============================================
   4
   5 1. How to test OTG FSM(HNP and SRP)
   6 -----------------------------------
   7
   8 To show how to demo OTG HNP and SRP functions via sys input files
   9 with 2 Freescale i.MX6Q sabre SD boards.
  10
  11 1.1 How to enable OTG FSM
  12 -------------------------
  13
  14 1.1.1 Select CONFIG_USB_OTG_FSM in menuconfig, rebuild kernel
  15 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  16
  17 Image and modules. If you want to check some internal
  18 variables for otg fsm, mount debugfs, there are 2 files
  19 which can show otg fsm variables and some controller registers value::
  20
  21         cat /sys/kernel/debug/ci_hdrc.0/otg
  22         cat /sys/kernel/debug/ci_hdrc.0/registers
  23
  24 1.1.2 Add below entries in your dts file for your controller node
  25 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  26
  27 ::
  28
  29         otg-rev = <0x0200>;
  30         adp-disable;
  31
  32 1.2 Test operations
  33 -------------------
  34
  35 1) Power up 2 Freescale i.MX6Q sabre SD boards with gadget class driver loaded
  36    (e.g. g_mass_storage).
  37
  38 2) Connect 2 boards with usb cable with one end is micro A plug, the other end
  39    is micro B plug.
  40
  41    The A-device(with micro A plug inserted) should enumerate B-device.
  42
  43 3) Role switch
  44
  45    On B-device::
  46
  47         echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
  48
  49    B-device should take host role and enumerate A-device.
  50
  51 4) A-device switch back to host.
  52
  53    On B-device::
  54
  55         echo 0 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
  56
  57    or, by introducing HNP polling, B-Host can know when A-peripheral wish
  58    to be host role, so this role switch also can be trigged in A-peripheral
  59    side by answering the polling from B-Host, this can be done on A-device::
  60
  61         echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req
  62
  63    A-device should switch back to host and enumerate B-device.
  64
  65 5) Remove B-device(unplug micro B plug) and insert again in 10 seconds,
  66    A-device should enumerate B-device again.
  67
  68 6) Remove B-device(unplug micro B plug) and insert again after 10 seconds,
  69    A-device should NOT enumerate B-device.
  70
  71    if A-device wants to use bus:
  72
  73    On A-device::
  74
  75         echo 0 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_drop
  76         echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req
  77
  78    if B-device wants to use bus:
  79
  80    On B-device::
  81
  82         echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
  83
  84 7) A-device power down the bus.
  85
  86    On A-device::
  87
  88         echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_drop
  89
  90    A-device should disconnect with B-device and power down the bus.
  91
  92 8) B-device does data pulse for SRP.
  93
  94    On B-device::
  95
  96         echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
  97
  98    A-device should resume usb bus and enumerate B-device.
  99
 100 1.3 Reference document
 101 ----------------------
 102 "On-The-Go and Embedded Host Supplement to the USB Revision 2.0 Specification
 103 July 27, 2012 Revision 2.0 version 1.1a"
 104
 105 2. How to enable USB as system wakeup source
 106 --------------------------------------------
 107 Below is the example for how to enable USB as system wakeup source
 108 at imx6 platform.
 109
 110 2.1 Enable core's wakeup::
 111
 112         echo enabled > /sys/bus/platform/devices/ci_hdrc.0/power/wakeup
 113
 114 2.2 Enable glue layer's wakeup::
 115
 116         echo enabled > /sys/bus/platform/devices/2184000.usb/power/wakeup
 117
 118 2.3 Enable PHY's wakeup (optional)::
 119
 120         echo enabled > /sys/bus/platform/devices/20c9000.usbphy/power/wakeup
 121
 122 2.4 Enable roothub's wakeup::
 123
 124         echo enabled > /sys/bus/usb/devices/usb1/power/wakeup
 125
 126 2.5 Enable related device's wakeup::
 127
 128         echo enabled > /sys/bus/usb/devices/1-1/power/wakeup
 129
 130 If the system has only one usb port, and you want usb wakeup at this port, you
 131 can use below script to enable usb wakeup::
 132
 133         for i in $(find /sys -name wakeup | grep usb);do echo enabled > $i;done;