[PATCH 3/3] mpc52xx/wdt: WDT uses GPT api

Grant Likely grant.likely at secretlab.ca
Wed Dec 9 08:21:54 EST 2009

On Tue, Dec 8, 2009 at 1:48 PM, Wim Van Sebroeck <wim at iguana.be> wrote:
> Hi Grant,
> Sorry for the delay, I need to deliver a project in a weeks time...


>> In actual fact, it is a single device with multiple functions, some of
>> which can be used at the same time.  The driver for the device
>> determines what the device instance supports and registers the
>> appropriate interfaces.  There is a GPIO controller, a PWM controller,
>> a general purpose timer, and the watchdog.  Because of the
>> multifunction nature of the device, there are subtle interactions
>> between the functions that the driver needs to maintain.  I don't want
>> to export functions from the driver which will only be used by a
>> watchdog instance.  I also don't want the added code and complexity of
>> a secondary probe path.  It is simpler and less code to roll all the
>> behaviour up into the one driver single driver that gets probed once.
>> >From the maintenance perspective, having the main driver in
>> arch/powerpc and the watchdog bit in drivers/watchdog doesn't really
>> help much anyway because anything that changes the internal driver API
>> (between the core and watchdog bits) will require cross-maintainer
>> changes.  ie. do changes go through my tree because they touch
>> arch/powerpc, or do they go through yours because they touch
>> drivers/watchdog?  I'd much rather all the internal details be
>> contained within a single driver.
> Your argument about maintenance is the same one as I have: If all watchdog
> driver pieces are under drivers/watchdog then it's easier for me to maintain
> them. (Definitely if we are doing clean-up work and API changes).


>> Besides, there is already precedence for very arch-specific drivers
>> living under arch/*/.  find ./arch -name *gpio*
> But in this case: I know where to find them and I will keep a mental note
> about this one. And yes indeed some very arch specific drivers can reside
> under arch/*/* .
> So please go ahead with pulling this one in a single driver.

Great, Thanks Wim.


Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

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