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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
1.1.1 Select CONFIG_USB_OTG_FSM in menuconfig, rebuild kernel
Image and modules. If you want to check some internal
variables for otg fsm, mount debugfs, 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
1.1.2 Add below entries in your dts file for your controller node
otg-rev = <0x0200>;
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
or, by introducing HNP polling, B-Host can know when A-peripheral wish
to be host role, so this role switch also can be trigged in A-peripheral
side by answering the polling from B-Host, this can be done on A-device:
echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_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;