On Mon, Jul 15, 2013 at 11:31:17PM -0700, Greg KH wrote: > On Tue, Jul 16, 2013 at 11:49:07AM +0800, Rong Wang wrote: > > Hi Greg, > > > > The USB on our platform can change roles between HOST and GADGET, but > > it is not capable of OTG. > > That kind of sounds like the definition of OTG :) > > > When the USB changes between roles the udev will run some scripts > > automatically according to the udev rules. > > What exactly does udev/userspace see when the roles change? > > And what can trigger the change in roles? > > > The default role is GADGET, and we bind the g_mass_storage to the USB > > GADGET role. > > > > We should secure the back end file storage between the device and the > > host PC connecting to our device. > > We need to know when the GADGET is really connect to a host PC, then > > we can umount the file on the device > > and export it to the g_mass_storage. > > I thought you already get an event for this, otherwise no one would be > able to properly deal with this. > > > The question is since we default GADGET, so the g_mass_storage.ko is > > installed early but connecting to a host PC > > is randomly, But the udev has no idea when a host PC connects our device. > > > > So we consider it's reasonable to let the udev know the GADGET device state. > > Is there any alternative to our question? > > I thought we already export events for gadget device states, have you > looked for them? I can't dig through the code at the moment, but this > seems like a pretty common issue... > If I understand correctly, what Rong wants is udev can be notified the udc state changes, like connect/disconnect event. Currently, we only export it to /sys. -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
