On Sat, Jun 11, 2016 at 11:03:53AM -0700, Guenter Roeck wrote:
> On 06/11/2016 12:05 AM, Oliver Neukum wrote:
> > On Fri, 2016-06-10 at 17:34 +0300, Heikki Krogerus wrote:
> > > +static ssize_t
> > > +preferred_role_store(struct device *dev, struct device_attribute
> > > *attr,
> > > + const char *buf, size_t size)
> > > +{
> > > + struct typec_port *port = to_typec_port(dev);
> > > + enum typec_role role;
> > > + int ret;
> > > +
> > > + mutex_lock(&port->lock);
> > > +
> > > + if (port->cap->type != TYPEC_PORT_DRP) {
> > > + dev_dbg(dev, "Try.SRC/SNK only supported with DRP
> > > ports\n");
> > > + ret = -EOPNOTSUPP;
> > > + goto out;
> > > + }
> >
> > I think Try.SNK with an UFP should fail differently from
> > Try.SRC and vice versa.
> >
>
> I think the message should not even mention Try.src or Try.snk
> in the first place, since both are optional and really orthogonal
> to how the role is set (it can also be changed with pd messages).
> On top of that, the specification states that Try.{src/snk} are
> optional if there is no PD support, and NA if PD is supported
> (see table 4.10). Kind of interesting, and I wonder how this
> is supposed to be implemented in practice, since Try.{src/snk}
> runs before it is established that/if the partner supports PD.
>
> A better message would be something like "Setting preferred
> role only supported with DRP ports", and leave implementation
> details to the port driver.
Works for me.
Thanks,
--
heikki
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