linux-kernel - Re: [PATCH v5 1/2] usb: USB Type-C connector class

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Message-ID: <20160817175840.GA4764@roeck-us.net>
Date:	Wed, 17 Aug 2016 10:58:40 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:	Greg KH <gregkh@...uxfoundation.org>,
	Oliver Neukum <oneukum@...e.com>,
	Felipe Balbi <felipe.balbi@...ux.intel.com>,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH v5 1/2] usb: USB Type-C connector class

On Wed, Aug 17, 2016 at 01:34:40PM +0300, Heikki Krogerus wrote:
> The purpose of USB Type-C connector class is to provide
> unified interface for the user space to get the status and
> basic information about USB Type-C connectors on a system,
> control over data role swapping, and when the port supports
> USB Power Delivery, also control over power role swapping
> and Alternate Modes.
> 
> Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> ---
[ ... ]

> +
> +static ssize_t current_power_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 = size;
> +
> +	if (!port->cap->usb_pd) {
> +		dev_dbg(dev, "power role swap only supported with USB PD\n");
> +		return -EOPNOTSUPP;
> +	}
> +
> +	if (!port->cap->pr_set) {
> +		dev_dbg(dev, "power role swapping not supported\n");
> +		return -EOPNOTSUPP;
> +	}
> +
> +	if (port->pwr_opmode != TYPEC_PWR_MODE_PD) {
> +		dev_dbg(dev, "partner unable to swap power role\n");
> +		return -EIO;
> +	}
> +
> +	if (!port->connected)
> +		return size;
> +
> +	ret = sysfs_strmatch(typec_roles, ARRAY_SIZE(typec_roles), buf);
> +	if (ret < 0)
> +		return ret;
> +
> +	role = ret;
> +
> +	ret = port->cap->pr_set(port->cap, role);

	if (ret)
missing.

> +		return ret;