Re: [PATCHv3 1/2] usb: USB Type-C connector class

[Guenter Roeck]

On 06/28/2016 06:12 AM, Heikki Krogerus wrote:
> On Mon, Jun 27, 2016 at 06:39:46AM -0700, Guenter Roeck wrote:
> > On 06/27/2016 05:13 AM, Heikki Krogerus wrote:
> > > Hi,
> > >
> > > On Mon, Jun 27, 2016 at 03:51:08PM +0530, Rajaram R wrote:
> > > > May be I am missing user or usage of the driver.. I see this driver is
> > > > providing limited information of the Type-C connectors or the port
> > > > partner
> > >
> > > Yes, this interface can't provide directly information received from
> > > PD commands like Discover Identity. We will have to present the
> > > partners even when USB PD is not supported and in a consistent
> > > fashion. Some details will be available in any case indirectly. Like
> > > if there are modes, there will be devices presenting them, and the
> > > product type in case of partners will be the partner type.
> > >
> > > But there are a couple of attributes I have been thinking about adding
> > > for the partners:
> > >
> > >           supported_data_roles
> > >           supports_usb_power_delivery
> > >
> > > The supported data roles would respond bits 30 and 31 of the ID Header
> > > VDO. But when the partner does not support USB PD, we will have to
> > > report "unknown" in it.
> >
> > Or make the attribute invisible in that case.
>
> Well, why not. I did not like the idea of hiding an attribute
> previously. I preferred to have an attribute always available, unless
> there was a single and clear way to determine the cases where any of
> the attributes for example with our partners would be visible or not..
> But who cares.

It would be visible if supports_usb_power_delivery is true. Doesn't that
match your requirements ?

> > > Oliver, Guenter! How do you guys feel about those? Is there any use
> > > for them?
> > Definitely good for debugging and informational. On the top of my head,
> > I don't immediately see what a user would do with it, though, but then
> > it would not hurt either to have the information.
> >
> > I keep wondering if it would make sense to directly expose the ID header
> > VDO, similar to the alternate mode VDOs, in the partner node.
>
> Yes, it makes sense. I'll add an attribute for that.
>
> But since you proposed hiding the attributes, I'll add an attribute
> "supports_usb_power_deliver" in any case, and make the vdo attribute
> visible only if it returs 1. I'll also make the "accessory" attribute
> visible only in case the partner type is accessory.
Ok with me.

Thanks,
Guenter