Messages in this thread | | | From | Alexandre Courbot <> | Date | Thu, 13 Mar 2014 13:46:15 +0900 | Subject | Re: [PATCH v2 1/5] gpiolib: Allow GPIO chips to request their own GPIOs |
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On Mon, Mar 10, 2014 at 9:54 PM, Mika Westerberg <mika.westerberg@linux.intel.com> wrote: > Sometimes it is useful to allow GPIO chips themselves to request GPIOs they > own through gpiolib API. One use case is ACPI ASL code that should be able > to toggle GPIOs through GPIO operation regions. > > We can't use gpio_request() because it will pin the module to the kernel > forever (it calls try_module_get()). To solve this we move module refcount > manipulation to gpiod_request() and let __gpiod_request() handle the actual > request. This changes the sequence a bit as now try_module_get() is called > outside of gpio_lock (I think this is safe, try_module_get() handles > serialization it needs already). > > Then we provide gpiolib internal functions gpiochip_request/free_own_desc() > that do the same as gpio_request() but don't manipulate module refrence > count. This allows the GPIO chip driver to request and free descriptors it > owns without being pinned to the kernel forever. > > Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
The change is clear and does not add too much complexity to the code, so no reason to oppose it.
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