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authorDmitry Torokhov <dmitry.torokhov@gmail.com>2013-01-08 09:10:31 -0800
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2013-01-09 09:07:56 -0800
commitb666263b71cb1f3b96fb79e69de7f119062b0da2 (patch)
tree3bc8324eb817042d2eef13f459a7d2b668892fd3 /drivers/input/input.c
parentbec7a4bbecf7da86b6e64bb78d22c92ea1ba4afe (diff)
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>
Diffstat (limited to 'drivers/input/input.c')
-rw-r--r--drivers/input/input.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/drivers/input/input.c b/drivers/input/input.c
index ce01332f7b3a..c04469928925 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -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,
* 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()
- * 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
* should not override it.
*/
-
struct input_dev *devm_input_allocate_device(struct device *dev)
{
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
* with input_unregister_device(); input_free_device() should not be
* 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)
{