Hi Peter, On Wed, Jul 17, 2013 at 10:36 AM, Peter Chen <peter.chen@xxxxxxxxxxxxx> wrote: > 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. OK. Thanks for your share. And you develop a new utility rather than udev to monitor that file? And you probably create a work queue in your udc driver to do this work? > > -- > > 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 -- 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
