Re: [PATCH v4 08/12] usb: roles: Add usb role switch notifier.

[Chen Yu]

Hi,

On 2019/3/19 19:56, Heikki Krogerus wrote:
> On Sat, Mar 16, 2019 at 11:53:38AM +0800, Yu Chen wrote:
>> This patch adds notifier for drivers want to be informed of the usb role switch.
>>
>> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>> Cc: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
>> Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
>> Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
>> Cc: John Stultz <john.stultz@xxxxxxxxxx>
>> Suggested-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
>> Signed-off-by: Yu Chen <chenyu56@xxxxxxxxxx>
>> ---
>>  drivers/usb/roles/class.c | 20 +++++++++++++++++++-
>>  include/linux/usb/role.h  | 46 ++++++++++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 65 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
>> index f45d8df5cfb8..e2caaa665d6e 100644
>> --- a/drivers/usb/roles/class.c
>> +++ b/drivers/usb/roles/class.c
>> @@ -20,6 +20,7 @@ struct usb_role_switch {
>>  	struct device dev;
>>  	struct mutex lock; /* device lock*/
>>  	enum usb_role role;
>> +	struct blocking_notifier_head nh;
>>  
>>  	/* From descriptor */
>>  	struct device *usb2_port;
>> @@ -49,8 +50,10 @@ int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role)
>>  	mutex_lock(&sw->lock);
>>  
>>  	ret = sw->set(sw->dev.parent, role);
>> -	if (!ret)
>> +	if (!ret) {
>>  		sw->role = role;
>> +		blocking_notifier_call_chain(&sw->nh, role, NULL);
>> +	}
>>  
>>  	mutex_unlock(&sw->lock);
>>  
>> @@ -58,6 +61,20 @@ int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role)
>>  }
>>  EXPORT_SYMBOL_GPL(usb_role_switch_set_role);
>>  
>> +int usb_role_switch_register_notifier(struct usb_role_switch *sw,
>> +				      struct notifier_block *nb)
>> +{
>> +	return blocking_notifier_chain_register(&sw->nh, nb);
>> +}
>> +EXPORT_SYMBOL_GPL(usb_role_switch_register_notifier);
>> +
>> +int usb_role_switch_unregister_notifier(struct usb_role_switch *sw,
>> +					struct notifier_block *nb)
>> +{
>> +	return blocking_notifier_chain_unregister(&sw->nh, nb);
>> +}
>> +EXPORT_SYMBOL_GPL(usb_role_switch_unregister_notifier);
>> +
>>  /**
>>   * usb_role_switch_get_role - Get the USB role for a switch
>>   * @sw: USB role switch
>> @@ -271,6 +288,7 @@ usb_role_switch_register(struct device *parent,
>>  		return ERR_PTR(-ENOMEM);
>>  
>>  	mutex_init(&sw->lock);
>> +	BLOCKING_INIT_NOTIFIER_HEAD(&sw->nh);
>>  
>>  	sw->allow_userspace_control = desc->allow_userspace_control;
>>  	sw->usb2_port = desc->usb2_port;
>> diff --git a/include/linux/usb/role.h b/include/linux/usb/role.h
>> index c05ffa6abda9..99d8b8e4fe61 100644
>> --- a/include/linux/usb/role.h
>> +++ b/include/linux/usb/role.h
>> @@ -42,6 +42,8 @@ struct usb_role_switch_desc {
>>  	bool allow_userspace_control;
>>  };
>>  
>> +
>> +#if IS_ENABLED(CONFIG_USB_ROLE_SWITCH)
>>  int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role);
>>  enum usb_role usb_role_switch_get_role(struct usb_role_switch *sw);
>>  struct usb_role_switch *usb_role_switch_get(struct device *dev);
>> @@ -51,5 +53,49 @@ struct usb_role_switch *
>>  usb_role_switch_register(struct device *parent,
>>  			 const struct usb_role_switch_desc *desc);
>>  void usb_role_switch_unregister(struct usb_role_switch *sw);
>> +int usb_role_switch_register_notifier(struct usb_role_switch *sw,
>> +				      struct notifier_block *nb);
>> +int usb_role_switch_unregister_notifier(struct usb_role_switch *sw,
>> +					struct notifier_block *nb);
>> +#else
>> +static inline int usb_role_switch_set_role(struct usb_role_switch *sw,
>> +		enum usb_role role)
>> +{
>> +	return 0;
>> +}
>> +
>> +static inline enum usb_role usb_role_switch_get_role(struct usb_role_switch *sw)
>> +{
>> +	return USB_ROLE_NONE;
>> +}
>> +
>> +static inline struct usb_role_switch *usb_role_switch_get(struct device *dev)
>> +{
>> +	return ERR_PTR(-ENODEV);
>> +}
>> +
>> +static inline void usb_role_switch_put(struct usb_role_switch *sw) { }
>> +
>> +static inline struct usb_role_switch *
>> +usb_role_switch_register(struct device *parent,
>> +			 const struct usb_role_switch_desc *desc)
>> +{
>> +	return ERR_PTR(-ENODEV);
>> +}
>> +
>> +static inline void usb_role_switch_unregister(struct usb_role_switch *sw) { }
>> +
>> +static int usb_role_switch_register_notifier(struct usb_role_switch *sw,
>> +				      struct notifier_block *nb)
>> +{
>> +	return -ENODEV;
>> +}
>> +
>> +static int usb_role_switch_unregister_notifier(struct usb_role_switch *sw,
>> +					struct notifier_block *nb)
>> +{
>> +	return -ENODEV;
>> +}
>> +#endif
>>  
>>  #endif /* __LINUX_USB_ROLE_H */
> 
> Sorry for the late response, but since you are providing a stub for
> all the functions, not just the new ones, could you please introduce
> them in a separate patch.
> 
> Add a patch where you introduce stubs for the exiting functions, and
> this patch can then add the stubs for just the new notifier functions.
> 
> 
> thanks,
> 

OK.

Thanks
Yu Chen