I have a overo earth+tobi interface running 2.6.39 kernel. I want to use a 2.0 USB 12MBPS GPS modem device with my gumstix as a host.
I tried to connect it to the USB host, but it never worked directly unless it was connected via a USB hub (non-external powered).
To understand why this is the case, I read on the Gumstix website that: Gumstix "Host" = USB High speed (480Mbit/s ONLY). You will need a hub to connect to most USB -> Serial adapters [http://gumstix.org/getting-started.html
But why is it '480Mbps ONLY'? The OMAP35x Technical Manual mentions that the USB host subsystem complies with USB 2.0 12 or 1.5 or 480 Mbps signals. Also it states that it complies with both EHCI and OHCI.
So how do I get my Gumstix to be configured to making such a USB connection to work... I did try to add the OHCI module in the kernel but it did not help. Is there any pin on the omap or a register value which I can use to ensure that OHCI is used instead?
It is interesting that many people provide the solution as using a USB hub. I know that is a solution, but I am a bit confused as to why I have to use it in the first place...
Furthermore, I don't mind using the OTG port - will it work there without a hub?
Thanks a lot for helping! I am a bit lost so will appreciate any suggestions.