Date: Fri, 3 Mar 2017 12:52:46 +0800
From: Peter Chen <hzpeterchen@gmail.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Greg KH <gregkh@linuxfoundation.org>,
        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: <20170303045246.GB18650@b29397-desktop>
References: <20170221142405.76299-1-heikki.krogerus@linux.intel.com>
 <20170221142405.76299-3-heikki.krogerus@linux.intel.com>
 <20170303033529.GA18650@b29397-desktop>
 <bbd1b0eb-7059-b72d-1fe4-27d9b5f84e0b@roeck-us.net>
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On Thu, Mar 02, 2017 at 08:29:07PM -0800, Guenter Roeck wrote:
> On 03/02/2017 07:35 PM, 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?
> 
> If it helps, my primary test system is a HP Chromebook 13 G1.
> 
> >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.
> 
> I don't really understand "What interface you use when you receive
> this event". Can you explain ?
> 

I mean "How to trigger kernel USB controller driver do role switch?"

> >
> >Eg, if "data_role" has changed, the udev can echo "data_role" to
> >/sys/class/usb-dual-role/role
> >
> That sounds like a kernel event delivered to user space via udev or
> sysfs notification and returned back into the kernel through a sysfs
> attribute. Do I understand that correctly ?
> 

Yes.

-- 

Best Regards,
Peter Chen