On Thu, 28 Aug 2014, Peter Chen wrote: > > DWC3 doesn't really have a pullup bit. It's got a RUN/STOP bit. Sure, it > > controls the pullups but it also kills the internal DMA and quite a bit > > of other internal blocks. > > It is the same with chipidea, it has RUN/STOP bit at usbcmd, and its > function is most like dwc3's. > > If the RUN/STOP bit is cleared at usb_gadget_driver.disconnect when > the cable is disconnected, when we set it again after cable is connected? > The UDC drivers who has vbus handler can set run/stop bit at .vbus_session, > but if the UDC drivers do not have vbus handler, where we can set it? Okay, so we need to add a "vbus_is_on" flag to the usb_gadget structure. The gadget driver will set this flag in its connect callback and clear the flag in its disconnect callback. If the UDC driver doesn't have a Vbus handler, it will invoke the connect callback just once during startup, and it will invoke the disconnect callback just once during removal. The gadget driver should include an adjust_pullup() routine. It should get called whenever a function is activated or deactivated, and also by the connect and disconnect callbacks. The logic is simple: If (any functions are deactivated) turn off the pullup else if (gadget->vbus_is_on) turn on the pullup else turn off the pullup How does that sound? Alan Stern -- 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
