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Input: document that unregistering managed devices is not necessary 

Apparently some users of managed input devices are confused whether
input_unregister_device() is needed when working with them. Clarify
this in the kernel doc for devm_input_allocate_device(): in most cases
there is no need to call neither input_unregister_device() nor
input_free_device() when working with managed devices.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Dmitry Torokhov 2013-01-08 09:10:31 -08:00
parent bec7a4bbec
commit b666263b71
1 changed files with 14 additions and 2 deletions
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16
drivers/input/input.c
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@ -1785,12 +1785,13 @@ static void devm_input_device_release(struct device *dev, void *res)
* its driver (or binding fails). Once managed input device is allocated, * its driver (or binding fails). Once managed input device is allocated,
* it is ready to be set up and registered in the same fashion as regular * it is ready to be set up and registered in the same fashion as regular
* input device. There are no special devm_input_device_[un]register() * input device. There are no special devm_input_device_[un]register()
* variants, regular ones work with both managed and unmanaged devices. * variants, regular ones work with both managed and unmanaged devices,
* should you need them. In most cases however, managed input device need
* not be explicitly unregistered or freed.
* *
* NOTE: the owner device is set up as parent of input device and users * NOTE: the owner device is set up as parent of input device and users
* should not override it. * should not override it.
*/ */
struct input_dev *devm_input_allocate_device(struct device *dev) struct input_dev *devm_input_allocate_device(struct device *dev)
{ {
struct input_dev *input; struct input_dev *input;
@ -2004,6 +2005,17 @@ static void devm_input_device_unregister(struct device *dev, void *res)
* Once device has been successfully registered it can be unregistered * Once device has been successfully registered it can be unregistered
* with input_unregister_device(); input_free_device() should not be * with input_unregister_device(); input_free_device() should not be
* called in this case. * called in this case.
*
* Note that this function is also used to register managed input devices
* (ones allocated with devm_input_allocate_device()). Such managed input
* devices need not be explicitly unregistered or freed, their tear down
* is controlled by the devres infrastructure. It is also worth noting
* that tear down of managed input devices is internally a 2-step process:
* registered managed input device is first unregistered, but stays in
* memory and can still handle input_event() calls (although events will
* not be delivered anywhere). The freeing of managed input device will
* happen later, when devres stack is unwound to the point where device
* allocation was made.
*/ */
int input_register_device(struct input_dev *dev) int input_register_device(struct input_dev *dev)
{ {