On Mon, Aug 18, 2014 at 10:27:36PM +0800, Alan Stern wrote:
> On Mon, 18 Aug 2014, Peter Chen wrote:
>
> > We introduce the connect API at usb_gadget_driver, the udc driver
> > uses it to tell gadget driver that it is ready to CONNECT, and the
> > dp can be pulled up from now on.
> >
> > Meanwhile, we introduce an API usb_udc_ready_to_connect to encapsulate
> > above operation.
> >
> > Signed-off-by: Peter Chen <[email protected]>
> > ---
> > include/linux/usb/gadget.h | 29 ++++++++++++++++++++++++++++-
> > 1 file changed, 28 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
> > index c3a6185..385af59 100644
> > --- a/include/linux/usb/gadget.h
> > +++ b/include/linux/usb/gadget.h
> > @@ -873,12 +873,39 @@ struct usb_gadget_driver {
> > void (*disconnect)(struct usb_gadget *);
> > void (*suspend)(struct usb_gadget *);
> > void (*resume)(struct usb_gadget *);
> > + int (*connect)(struct usb_gadget *, bool connect);
> >
> > /* FIXME support safe rmmod */
> > struct device_driver driver;
> > };
>
> This looks strange. Why do you have the "bool connect" parameter?
How can I tell the gadget driver to pull down dp after vbus is off?
> There's already a disconnect callback.
Maybe I need to use other name rather than connect, the .disconnect sometimes
is called at bus reset handler so I can't put dp control in it.
> Also, you forgot to update the kerneldoc.
>
Will do.
> > -
> > +/**
> > + * usb_udc_ready_to_connect - The udc is ready to connect (physical pullup
> > dp)
> > + * @driver: the gadget driver for this gadget
> > + * @gadget: the udc device
> > + * @connect: whether the udc is ready to connect or not
> > + *
> > + * The USB 2.0 spec 7.2.1 and 7.1.5 requires the dp should not be pulled
> > up if
> > + * the vbus is not there, else it will fail Back-voltage Testing at below
> > + * USB-IF certification test.
> > + * www.usb.org/developers/docs/USB-IFTestProc1_3.pdf
> > + *
> > + * Some udcs have hardware logic that even the pullup bit is set by
> > software,
> > + * it can still meet above Back-voltage Testing requirement, these kinds of
> > + * udcs only need to set connect as true at its .udc_start. But other udcs
> > + * may have no this capability, so they need the software pullup bit is not
> > + * set when the vbus is not there, otherwise it will break the spec, and
> > can't
> > + * pass Back-voltage Testing. So they need to set connect as false when the
> > + * vbus is not there, and set connect as true when the vbus is there.
> > + */
> > +static inline int usb_udc_ready_to_connect(struct usb_gadget_driver
> > *driver,
> > + struct usb_gadget *gadget, bool connect)
> > +{
> > + if (driver->connect)
> > + return driver->connect(gadget, connect);
> > + else
> > + return -EOPNOTSUPP;
> > +}
> >
> >
> > /*-------------------------------------------------------------------------*/
>
> Again, the "connect" argument isn't needed.
>
--
Best Regards,
Peter Chen
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