USB Chainsaw

There is no mechanism for transfering data directly between USB host controllers. You can't connect one PC USB host port to a second PC and do anything useful. Some controllers (not PC ones) ate OTG controllers which means they can switch role from host to device but the OTG spec has its own set of connectors and cables (there is an extra signal IIRC that designates which end is the default host). An 'A' to 'A' cable would require a device in the middle that appears as such to each of the hosts and defines some means to pass data across.

I'm guessing that "usb widget support" for Linux means that the Linux system has a USB device port and that a PC, or whatever, USB host can control it. A photoframe might be an example of that.

Peter

eed

Yes, the ability to switch roles (OTG or otherwise) is first a hardware capability, which then needs to be supported in the operating system's USB implementation. The palm pre for example is believed to have hardware which could be OTG capable (unless precluded by some detail of PCB layout or PHY hookup) but the current software operates only in device mode.

USB "gadget" is a linux device-side interface system often used in embedded linux systems to emulate a USB mass storage device (point it at a local partition or image file), provide a network interface over USB, etc or I believe in the latest version potentially a combination.

I haven't looked into it, but I think that in an OTG device "gadget" would only handle the device mode - you'd switch it it host mode at a lower driver level and it would presumably then behave like the linux USB host implementation.