Changes between Version 5 and Version 6 of linux/OTG


Ignore:
Timestamp:
04/24/2020 04:58:59 PM (2 years ago)
Author:
Tim Harvey
Comment:

added section about using a Non-OTG port in device-mode

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  • linux/OTG

    v5 v6  
    401401echo host > /sys/kernel/debug/ci_hdrc.0/role # specify host mode
    402402}}}
     403
     404
     405[=#device-mode]
     406== Using a Non-OTG port in device mode
     407In some cases you can use a USB Type-A socket in device mode in a non-standard way. This can be used for example on boards that route a USB OTG controller to a Type-A socket which does not have an OTG_ID signal. In this case you need to isolate VBUS to ensure both the host and the device are not both driving it at the same time. This opportunity exists on certain Ventana boards (where the 'usbotg' host controller is enabled in the device-tree yet the signals route to a USB Type-A socket connector instead of an OTG controller).
     408
     409In this case you can do the following:
     4101. use a non-standard Type-A plug to Type-A plug cable and isolate the VBUS (red wire) to ensure host and device are not both driving VBUS
     4112. configure the OTG controller for device-mode (see [#dual-role above])
     4123. Load a gadget driver (see [#device above])