Changes between Version 5 and Version 6 of linux/OTG

Timestamp:

04/24/2020 04:58:59 PM (5 years ago)

Author:

Tim Harvey

Comment:

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

linux/OTG

@@ -401 +401 @@
 echo host > /sys/kernel/debug/ci_hdrc.0/role # specify host mode
 }}}
+
+
+[=#device-mode]
+== Using a Non-OTG port in device mode
+In 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).
+
+In this case you can do the following:
+1. 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
+2. configure the OTG controller for device-mode (see [#dual-role above])
+3. Load a gadget driver (see [#device above])