Re: [PATCHv4] usb: typec: Add a sysfs node to manage port type

[Badhri Jagan Sridharan]

On Fri, May 26, 2017 at 10:43 PM, Greg Kroah-Hartman
 wrote:
> On Fri, May 26, 2017 at 01:42:57PM -0700, 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 
>> ---
>> 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
>
> Ok, this is how you write a changelog for a patch, very nice job!

Thanks Greg :)

>
> greg k-h
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Re: [PATCHv4] usb: typec: Add a sysfs node to manage port type

[Greg Kroah-Hartman]

On Fri, May 26, 2017 at 01:42:57PM -0700, 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 
> ---
> 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

Ok, this is how you write a changelog for a patch, very nice job!

greg k-h
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[PATCHv4] usb: typec: Add a sysfs node to manage port type

[Badhri Jagan Sridharan]

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 
---
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 
 #include 
+#include 
 #include 
 #include 
 
@@ -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_typeport_type;
+   struct mutexport_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_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_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_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_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,