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Date: Fri, 26 May 2017 19:24:59 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Badhri Jagan Sridharan <badhri@...gle.com>,
Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Oliver Neukum <oneukum@...e.com>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] usb: typec: Add a sysfs node to manage port type
On 05/26/2017 04:07 PM, Badhri Jagan Sridharan wrote:
> User space applications in some cases have the need to enforce a
> specific port type(DFP/UFP/DRP). This change allows userspace to
> attempt setting the desired port type. Low level drivers can
> however reject the request if the specific port type is not supported.
>
> Signed-off-by: Badhri Jagan Sridharan <Badhri@...gle.com>
> ---
> Changelog since v1:
> - introduced a new variable port_type in struct typec_port to track
> the current port type instead of changing type member in
> typec_capability to address Heikki Krogerus comments.
> - changed the output format and strings that would be displayed as
> suggested by Heikki Krogerus.
>
> Changelog since v2:
> - introduced a new mutex lock to protect port_type for addressing
> the race conditions identified by Geunter Roeck
> - added typec_port_types_drp for printing port_type when cap->type
> is TYPE_PORT_DRP as suggested by Geunter Roeck
> - Power role swap and data role swaps would be rejected unless
> port port_type == TYPE_PORT_DRP
> - port_type_store would return immediately if the current port_type
> is same as the new port_type as suggested by Geunter Roeck
>
> Changelog since v3:
> - Moved as much as code outside port_type_lock as suggested by
> Geunter Roeck
> - Removed Change-Id line from commit message identified by
> Greg Kroah-Hartman
>
> drivers/usb/typec/typec.c | 106 +++++++++++++++++++++++++++++++++++++++++-----
> include/linux/usb/typec.h | 4 ++
> 2 files changed, 100 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/usb/typec/typec.c b/drivers/usb/typec/typec.c
> index 89e540bb7ff3..bf1eb11c6646 100644
> --- a/drivers/usb/typec/typec.c
> +++ b/drivers/usb/typec/typec.c
> @@ -11,6 +11,7 @@
>
> #include <linux/device.h>
> #include <linux/module.h>
> +#include <linux/mutex.h>
> #include <linux/slab.h>
> #include <linux/usb/typec.h>
>
> @@ -69,6 +70,8 @@ struct typec_port {
> enum typec_role pwr_role;
> enum typec_role vconn_role;
> enum typec_pwr_opmode pwr_opmode;
> + enum typec_port_type port_type;
> + struct mutex port_type_lock;
>
> const struct typec_capability *cap;
> };
> @@ -789,6 +792,18 @@ static const char * const typec_data_roles[] = {
> [TYPEC_HOST] = "host",
> };
>
> +static const char * const typec_port_types[] = {
> + [TYPEC_PORT_DFP] = "source",
> + [TYPEC_PORT_UFP] = "sink",
> + [TYPEC_PORT_DRP] = "dual",
> +};
> +
> +static const char * const typec_port_types_drp[] = {
> + [TYPEC_PORT_DFP] = "dual [source] sink",
> + [TYPEC_PORT_UFP] = "dual source [sink]",
> + [TYPEC_PORT_DRP] = "[dual] source sink",
> +};
> +
> static ssize_t
> preferred_role_store(struct device *dev, struct device_attribute *attr,
> const char *buf, size_t size)
> @@ -846,11 +861,6 @@ static ssize_t data_role_store(struct device *dev,
> struct typec_port *port = to_typec_port(dev);
> int ret;
>
> - if (port->cap->type != TYPEC_PORT_DRP) {
> - dev_dbg(dev, "data role swap only supported with DRP ports\n");
> - return -EOPNOTSUPP;
> - }
> -
> if (!port->cap->dr_set) {
> dev_dbg(dev, "data role swapping not supported\n");
> return -EOPNOTSUPP;
> @@ -860,11 +870,22 @@ static ssize_t data_role_store(struct device *dev,
> if (ret < 0)
> return ret;
>
> + mutex_lock(&port->port_type_lock);
> + if (port->port_type != TYPEC_PORT_DRP) {
> + dev_dbg(dev, "port type fixed at \"%s\"",
> + typec_port_types[port->port_type]);
> + ret = -EOPNOTSUPP;
> + goto unlock_and_ret;
> + }
> +
> ret = port->cap->dr_set(port->cap, ret);
> if (ret)
> - return ret;
> + goto unlock_and_ret;
>
> - return size;
> + ret = size;
> +unlock_and_ret:
> + mutex_unlock(&port->port_type_lock);
> + return ret;
> }
>
> static ssize_t data_role_show(struct device *dev,
> @@ -885,7 +906,7 @@ static ssize_t power_role_store(struct device *dev,
> const char *buf, size_t size)
> {
> struct typec_port *port = to_typec_port(dev);
> - int ret = size;
> + int ret;
>
> if (!port->cap->pd_revision) {
> dev_dbg(dev, "USB Power Delivery not supported\n");
> @@ -906,11 +927,22 @@ static ssize_t power_role_store(struct device *dev,
> if (ret < 0)
> return ret;
>
> + mutex_lock(&port->port_type_lock);
> + if (port->port_type != TYPEC_PORT_DRP) {
> + dev_dbg(dev, "port type fixed at \"%s\"",
> + typec_port_types[port->port_type]);
> + ret = -EOPNOTSUPP;
> + goto unlock_and_ret;
> + }
> +
> ret = port->cap->pr_set(port->cap, ret);
> if (ret)
> - return ret;
> + goto unlock_and_ret;
>
> - return size;
> + ret = size;
> +unlock_and_ret:
> + mutex_unlock(&port->port_type_lock);
> + return ret;
> }
>
> static ssize_t power_role_show(struct device *dev,
> @@ -926,6 +958,57 @@ static ssize_t power_role_show(struct device *dev,
> }
> static DEVICE_ATTR_RW(power_role);
>
> +static ssize_t
> +port_type_store(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t size)
> +{
> + struct typec_port *port = to_typec_port(dev);
> + int ret;
> + enum typec_port_type type;
> +
> + if (!port->cap->port_type_set || port->cap->type != TYPEC_PORT_DRP) {
> + dev_dbg(dev, "changing port type not supported\n");
> + return -EOPNOTSUPP;
> + }
> +
> + ret = sysfs_match_string(typec_port_types, buf);
> + if (ret < 0)
> + return ret;
> +
> + mutex_lock(&port->port_type_lock);
> + type = ret;
> +
Can be outside lock.
> + if (port->port_type == type) {
> + ret = size;
> + goto unlock_and_ret;
> + }
> +
> + ret = port->cap->port_type_set(port->cap, type);
> + if (ret)
> + goto unlock_and_ret;
> +
> + port->port_type = type;
> + ret = size;
> +
> +unlock_and_ret:
> + mutex_unlock(&port->port_type_lock);
> + return size;
return ret;
> +}
> +
> +static ssize_t
> +port_type_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct typec_port *port = to_typec_port(dev);
> +
> + if (port->cap->type == TYPEC_PORT_DRP)
> + return sprintf(buf, "%s\n",
> + typec_port_types_drp[port->port_type]);
> +
> + return sprintf(buf, "[%s]\n", typec_port_types[port->cap->type]);
> +}
> +static DEVICE_ATTR_RW(port_type);
> +
> static const char * const typec_pwr_opmodes[] = {
> [TYPEC_PWR_MODE_USB] = "default",
> [TYPEC_PWR_MODE_1_5A] = "1.5A",
> @@ -1035,6 +1118,7 @@ static struct attribute *typec_attrs[] = {
> &dev_attr_usb_power_delivery_revision.attr,
> &dev_attr_usb_typec_revision.attr,
> &dev_attr_vconn_source.attr,
> + &dev_attr_port_type.attr,
> NULL,
> };
> ATTRIBUTE_GROUPS(typec);
> @@ -1211,6 +1295,8 @@ struct typec_port *typec_register_port(struct device *parent,
>
> port->id = id;
> port->cap = cap;
> + port->port_type = cap->type;
> + mutex_init(&port->port_type_lock);
> port->prefer_role = cap->prefer_role;
>
> port->dev.class = typec_class;
> diff --git a/include/linux/usb/typec.h b/include/linux/usb/typec.h
> index ec78204964ab..b174248af7c9 100644
> --- a/include/linux/usb/typec.h
> +++ b/include/linux/usb/typec.h
> @@ -190,6 +190,7 @@ struct typec_partner_desc {
> * @pr_set: Set Power Role
> * @vconn_set: Set VCONN Role
> * @activate_mode: Enter/exit given Alternate Mode
> + * @port_type_set: Set port type
> *
> * Static capabilities of a single USB Type-C port.
> */
> @@ -214,6 +215,9 @@ struct typec_capability {
>
> int (*activate_mode)(const struct typec_capability *,
> int mode, int activate);
> + int (*port_type_set)(const struct typec_capability *,
> + enum typec_port_type);
> +
> };
>
> /* Specific to try_role(). Indicates the user want's to clear the preference. */
>
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