Re: [PATCH v10 08/14] usb: otg: add OTG/dual-role core

[Sergei Shtylyov]

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? :-)

> --
> cheers,
> -roger

MBR, Sergei