I'm writing a bus driver, and I'm confused.
If I create a class and class devices, I can set a release method on
the class. But if I create a bus, there's no bus_type.dev_release.
Am I really supposed to manually set .release on each struct device
that I enumerate? If so, why?
--Andy
--
Andy Lutomirski
AMA Capital Management, LLC
On Wed, Nov 25, 2015 at 08:21:36AM -0800, Andy Lutomirski wrote:
> I'm writing a bus driver, and I'm confused.
Yeah, writing a new bus is a major pain, I keep meaning to work on the
api every year or so when I have to write a new one, but then I just
suffer through it and never get around to it :(
> If I create a class and class devices, I can set a release method on
> the class. But if I create a bus, there's no bus_type.dev_release.
> Am I really supposed to manually set .release on each struct device
> that I enumerate? If so, why?
No, you shouldn't have to do that, the "struct device_type" that is
assigned to your device has a .release callback, that is what will be
called. Make sure you set that for each device you create for your bus.
hope this helps,
greg k-h
On Wed, Nov 25, 2015 at 8:37 AM, Greg KH <[email protected]> wrote:
> On Wed, Nov 25, 2015 at 08:21:36AM -0800, Andy Lutomirski wrote:
>> I'm writing a bus driver, and I'm confused.
>
> Yeah, writing a new bus is a major pain, I keep meaning to work on the
> api every year or so when I have to write a new one, but then I just
> suffer through it and never get around to it :(
>
>> If I create a class and class devices, I can set a release method on
>> the class. But if I create a bus, there's no bus_type.dev_release.
>> Am I really supposed to manually set .release on each struct device
>> that I enumerate? If so, why?
>
> No, you shouldn't have to do that, the "struct device_type" that is
> assigned to your device has a .release callback, that is what will be
> called. Make sure you set that for each device you create for your bus.
>
> hope this helps,
>
It does, thanks.
One more question: device_destroy seems to be the opposite of
device_create. But device_destroy does put_device and
device_unregister, and device_unregister also does put_device. That
suggests that device_create returns a device with *two* references.
How does that happen?
I'm having trouble reconciling this with the fact that device_register
followed immediately by device_unregister appears to release the
device.
Is there some reference counting subtlety I'm missing?
--Andy
--
Andy Lutomirski
AMA Capital Management, LLC