On 10/06/16 13:44, Sergei Shtylyov wrote: > On 6/10/2016 1:19 PM, Roger Quadros wrote: > >>>> It provides APIs for the following tasks >>>> >>>> - Registering an OTG/dual-role capable controller >>>> - Registering Host and Gadget controllers to OTG core >>>> - Providing inputs to and kicking the OTG state machine >>>> >>>> Provide a dual-role device (DRD) state machine. >>>> DRD mode is a reduced functionality OTG mode. In this mode >>>> we don't support SRP, HNP and dynamic role-swap. >>>> >>>> In DRD operation, the controller mode (Host or Peripheral) >>>> is decided based on the ID pin status. Once a cable plug (Type-A >>>> or Type-B) is attached the controller selects the state >>>> and doesn't change till the cable in unplugged and a different >>>> cable type is inserted. >>>> >>>> As we don't need most of the complex OTG states and OTG timers >>>> we implement a lean DRD state machine in usb-otg.c. >>>> The DRD state machine is only interested in 2 hardware inputs >>>> 'id' and 'b_sess_vld'. >>>> >>>> Signed-off-by: Roger Quadros <rogerq@xxxxxx> >>> >> >> <snip> >> >>> [...] >>>> +/** >>>> + * usb_otg_register_gadget - Register the gadget controller to OTG core >>>> + * @gadget: gadget controller >>> >>> We call that USB device controller (UDC). I'm not sure what you meant here... >>> And what about the 2nd arg, 'ops'? >> >> There are 2 data structures representing the Device controller. >> >> struct usb_gadget - represents a usb slave device >> struct usb_udc -struct usb_udc - describes one usb device controller >> >> usb_udc is for private use only. usb_otg_register_gadget() takes struct usb_gadget >> as argument. >> >> Do you want me to refer to struct usb_gadget as UDC? > > No. > >> What is wrong with calling it gadget controller? > > It's not a controller, it's a piece of software AFAIU. Or is my English just too weak? :-) Everything at this point is a piece of software :). struct usb_gadget, represents the gadget controller device not the driver (or software). struct usb_gadget_driver represents the gadget function driver. struct usb_gadget_ops represents the UDC driver ops. -- cheers, -roger -- 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
