On 09/04/2013 10:16 AM, Greg KH wrote: > On Wed, Sep 04, 2013 at 09:17:02AM +0900, Chanwoo Choi wrote: >> On 09/04/2013 12:57 AM, Greg KH wrote: >>> On Mon, Sep 02, 2013 at 10:13:44AM +0900, Chanwoo Choi wrote: >>>> Hi Greg, >>>> >>>> On 09/02/2013 09:40 AM, Greg KH wrote: >>>>> On Mon, Sep 02, 2013 at 09:20:08AM +0900, Chanwoo Choi wrote: >>>>>> This patch remove extcon_dev_register()'s second parameter which means >>>>>> the pointer of parent device to simplify prototype of this function. >>>>> >>>>> No, please don't. You want the parent to be passed in, as the core >>>>> needs it when it is registered with the system, otherwise it will not >>>>> show up in sysfs properly (i.e. you can't set it afterwards.) >>>> >>>> Currently, each extcon driver have allocated memory for extcon device >>>> by using devm_kzalloc() in each extcon device driver. >>> >>> That seems backwards, the extcon core should be the one doing the >>> allocation, and ownership of the device, like all other subsystem cores >>> do. That makes the driver logic much simpler, and the lifetime >>> ownership correct (i.e. what happens when a device is unbound from a >>> driver by userspace? The driver can't control the device memory >>> anymore...) >>> >> >> OK, >> The extcon core will control memory allocation instead of extcon device >> driver >> as following. >> - devm_extcon_allocate_device(struct device *dev) > > Huh? Why do you need a devm allocator? This is a "real" child device, > just create it with a "extcon_create_device()" or some such call, like > all other busses do?
I refer Input/IIO subsystem to check the process of device registration. Input subsystem has following functions for memory allocation of input device and input device registration. Input subsystem - struct input_dev *devm_input_allocate_device(struct device *device) - struct input_dev *input_allocate_device(void) - int input_register_device(struct input_dev *dev) drivers/input/input.c devm_input_allocate_device()/input_allocate_device() can allocate memory for input device in input core. And then created input device pass input_register_device() as parameter. So, input device driver haven't executed kmalloc() or devm_kmalloc() to allocate memory of input device by using input_allocate_device()/ devm_input_allocate_device(). Also,IIO subsystem has separate iio_device_alloc() function to allocate memory for iio device. But IIO subsystem hasn't "devm_" allocator. So, If iio device driver fail initialization in *_probe, should execute iio_device_free() to free allocated memory. IIO Subsystem - iio_device_alloc(int sizeof_priv) - iio_device_register(struct iio_dev *indio_dev); drivers/iio/industrialio-core.c So, I think extcon subsystem need extcon_allocate_device()/devm_extcon_allocate_device() to allocate for memory extcon device. To implement devm_extcon_allocate_device() function , extcon subsystem need extcon_allocate_device() because devm_extcon_allocate_device() must call extcon_allocate_device for memory allocation. If extcon_allocate_device()/devm_extcon_allocate_device() is implemented to extcon core, I think extcon core can control the memory operation of extcon device. EXTCON Subsystem - devm_extcon_allocate_device(struct device *dev) - extcon_allocate_device(void) - extcon_dev_register(struct extcon_dev *edev) If I'm wrong, please correct me. Thanks. Best Regards, Chanwoo Choi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
