Documentation/usb/chipidea.rst

Source file repositories/reference/linux-study-clean/Documentation/usb/chipidea.rst

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Documentation/usb/chipidea.rst
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Support Tooling And Documentation
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Documentation
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Support Tooling And Documentation: documentation
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Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

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==============================================
ChipIdea Highspeed Dual Role Controller Driver
==============================================

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>;
	adp-disable;

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: one end is micro A plug, the other end
   is micro B plug.

   The A-device (with micro A plug inserted) should enumerate 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 enumerate 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

   or, by introducing HNP polling, B-Host can know when A-peripheral wishes to
   be in the host role, so this role switch also can be triggered 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 enumerate B-device.

5) Remove B-device (unplug micro B plug) and insert again in 10 seconds;
   A-device should enumerate B-device again.

6) Remove B-device (unplug micro B plug) and insert again after 10 seconds;
   A-device should NOT enumerate B-device.

Annotation

Implementation Notes