I need to use an embedded Linux platform as a USB device in order to stream audio and video from a smartphone. The platform has a USB A receptacle and doesn't support OTG (USB_ID pin is not connected on the host controller).
Now I try to switch from host to device mode using DWC3 controller and the debugfs interface. Therefore I activated DWC3 controller in the kernel configuration and set it to "Dual Role Mode". After mounting the file system I checked the current mode in /sys/kernel/debug/xxxxxxxx.usb3/mode with cat mode and got host as expected. But unfortunately I can't write device to the mode file. After entering the command echo device > mode it remains host and does not change. Does anyone know what could be causing it?