Re: [RFC PATCHv2] usb: USB Type-C Connector Class

[Guenter Roeck]

On 05/25/2016 04:30 AM, Heikki Krogerus wrote:
> Hi,
>
> On Tue, May 24, 2016 at 06:42:09AM -0700, Guenter Roeck wrote:
> > > +struct typec_capability {
> > > +	enum typec_data_role	role;
> > > +	unsigned int		usb_pd:1;
> > > +	struct typec_altmode	*alt_modes;
> > > +	unsigned int		audio_accessory:1;
> > > +	unsigned int		debug_accessory:1;
> > > +
> > > +	int			(*fix_role)(struct typec_port *,
> > > +					    enum typec_data_role);
> > > +
> > > +	int			(*dr_swap)(struct typec_port *);
> > > +	int			(*pr_swap)(struct typec_port *);
> > > +	int			(*vconn_swap)(struct typec_port *);
> > > +
> >
> > The function parameter in those calls is all but useless to the caller.
> > It needs to store the typec_port returned from typec_register(), create a
> > list of ports, and then search through this list each time one of the
> > functions is called. This is quite expensive for no good reason.
> >
> > Previously, with typec_port exported, the called code could use the stored
> > caps pointer to map to its internal data structures. This is no longer
> > possible.
>
> True, the API now is in practice broken.
>
> > I think it would be useful to provide a better means for the called function
> > to identify its context. Maybe provide a pointer to the private data in
> > the registration function and use it as parameter in the callback functions ?
>
> Sounds reasonable.

I'll send a follow-up patch hopefully later today which fixes all the problems
I have found so far.

Guenter