On Mon, Aug 29, 2016 at 06:04:52AM -0700, Guenter Roeck wrote: > Heikki, > > On 08/26/2016 07:07 AM, Heikki Krogerus wrote: > > > > > > > > +What: /sys/class/typec/<port>-partner/type > > > > > > +Date: June 2016 > > > > > > +Contact: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx> > > > > > > +Description: > > > > > > + Shows the type of the partner. Can be one of the following: > > > > > > + - USB - When the partner is normal USB host/peripheral. > > > > > > + - Charger - When the partner has been identified as dedicated > > > > > > + charger. > > > > > > + - Alternate Mode - When the partner supports Alternate Modes. > > > > > > + - Accessory - When the partner is one of the accessories with > > > > > > + specific Accessory Mode defined in USB Type-C > > > > > > + specification. > > > > > > > > > > > > > > > where a dock would be classified ? > > > > > > > > A dock is just USB PD capable device with a bunch of alternate modes > > > > that is attached to the port. There is no specific identifier for a > > > > "dock". > > > > > > My remark was a bit too stern, > > > I meant a dock might be 'USB' 'Charger' 'Alternate Mode' , all at the > > > same time or alternately depending what you plug in. > > > I don't really see those types as mutually exclusive. > > > > So USB type means the partner does not have alternate modes (I'll > > clear that in the documentation), Charger is a dedicated charger and > > therefore can not be anything else (no USB, no alternate modes). > > > > This is probably the most difficult attribute to support. > > Many PD capable chargers support alternate modes (for firmware upgrades). > As I mentioned earlier, it is difficult to match reported Type-C partner > types (or really anything reported in the SVDM Identity command) > to the above types. > > Does it really make sense to deviate that much from the Type-C specification ? > I can understand why you hesitate to use DFP / UFP, as those terms are > really hard to understand for the non-initiated. However, here it is really > difficult to even determine which value to set. The best I can come up with is > > - Not PD capable. Report USB (obviously includes non-PD capable chargers) > - PD capable, supports alternate modes. Report as Alternate Mode (including > PD chargers supporting alternate modes) > - PD capable, does not support alternate modes. Report as Accessory if > connected as accessory, as charger if we the port is connected as sink, > USB otherwise > > Overall this is quite vague and, especially for chargers, most of the time > misses the point. > > I would really prefer if we could stay closer to the specification in this > case, and not try to merge multiple orthogonal attributes into one. OK. So what would you propose? Thanks, -- heikki -- 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
