Date: Fri, 3 Mar 2017 16:31:33 +0200
From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
To: Peter Chen <hzpeterchen@gmail.com>
Cc: Greg KH <gregkh@linuxfoundation.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Felipe Balbi <felipe.balbi@linux.intel.com>,
        Oliver Neukum <oneukum@suse.com>, linux-kernel@vger.kernel.org,
        linux-usb@vger.kernel.org, Roger Quadros <rogerq@ti.com>,
        Jun Li <jun.li@nxp.com>
Subject: Re: [PATCH v17 2/3] usb: USB Type-C connector class
Message-ID: <20170303143133.GB6999@kuha.fi.intel.com>
References: <20170221142405.76299-1-heikki.krogerus@linux.intel.com>
 <20170221142405.76299-3-heikki.krogerus@linux.intel.com>
 <20170303033529.GA18650@b29397-desktop>
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Hi Peter,

On Fri, Mar 03, 2017 at 11:35:29AM +0800, Peter Chen wrote:
> On Tue, Feb 21, 2017 at 05:24:04PM +0300, Heikki Krogerus wrote:
> > +/* --------------------------------------- */
> > +/* Driver callbacks to report role updates */
> > +
> > +/**
> > + * typec_set_data_role - Report data role change
> > + * @port: The USB Type-C Port where the role was changed
> > + * @role: The new data role
> > + *
> > + * This routine is used by the port drivers to report data role changes.
> > + */
> > +void typec_set_data_role(struct typec_port *port, enum typec_data_role role)
> > +{
> > +	if (port->data_role == role)
> > +		return;
> > +
> > +	port->data_role = role;
> > +	sysfs_notify(&port->dev.kobj, NULL, "data_role");
> > +	kobject_uevent(&port->dev.kobj, KOBJ_CHANGE);
> > +}
> > +EXPORT_SYMBOL_GPL(typec_set_data_role);
> > +
> 
> Hi Keikki,
> 
> Have you tested this interface with real dual-role controller/board?

Yes. Our boards are mostly USB dual-role capable.

> What interface you use when you receive this event to handle
> dual-role switch? I am wonder if a common dual-role class is
> needed, then we can have a common user utility.
> 
> Eg, if "data_role" has changed, the udev can echo "data_role" to
> /sys/class/usb-dual-role/role

No. If the partner executes successfully for example DR_Swap message,
the kernel has to take care everything that is needed for the role to
be what ever was negotiated on its own. User space can't be involved
with that.


Thanks,

-- 
heikki