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Date: Fri, 3 Mar 2017 11:35:29 +0800
From: Peter Chen <hzpeterchen@gmail.com>
To: Heikki Krogerus <heikki.krogerus@linux.intel.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: <20170303033529.GA18650@b29397-desktop>
References: <20170221142405.76299-1-heikki.krogerus@linux.intel.com>
 <20170221142405.76299-3-heikki.krogerus@linux.intel.com>
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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?
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

Maybe we can enhance Roger's drd framework [1] to fulfill that.

[1] https://lwn.net/Articles/682531/
-- 

Best Regards,
Peter Chen