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Diffstat (limited to 'kernel/Documentation/usb/chipidea.txt')
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diff --git a/kernel/Documentation/usb/chipidea.txt b/kernel/Documentation/usb/chipidea.txt new file mode 100644 index 000000000..3f848c1f2 --- /dev/null +++ b/kernel/Documentation/usb/chipidea.txt @@ -0,0 +1,92 @@ +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; + |