Hi,
we would like to use the USB OTG controller included in the DM3730 SoC as a serial gadget (device) only in our custom board. As this only would require peripheral mode of operation we would like to disable the possibility of using host mode or negotiation with other OTG devices.
As it is stated in [1] and [2], fixing the ID signal of the transceiver to high would make the controller to be initiated as peripheral (device) mode, which is what we want and is OK. This would theoretically make any other peripheral connected to this port to be ignored, only allowing host devices to be connected (i.e. a USB host PC for using the USB serial with hyperterminal).
However, according to the information in [1] (OTG section), if another OTG device is connected a HNP negotiation process will begin. This would not be desired in our application.
Provided the fact we are using las mainline linux kernel 2.6.37, is there any way to prevent OTG controller to use HNP? Can we force it to perform only as device?
Thank you.
[1] http://www.linux-usb.org/gadget/h2-otg.html
[2] http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/100/p/7621/30117.aspx#30117