Re: [PATCH 6/7] staging:iio:dummy: Add DMA buffer support

[Lars-Peter Clausen <lars@metafoo.de>]

On 10/04/2015 05:57 PM, Jonathan Cameron wrote:
> On 02/10/15 15:45, Lars-Peter Clausen wrote:
>> Add a DMA buffer implementation to the IIO dummy driver. Similar to the
>> existing kfifo based dummy buffer implementation the buffer is not
>> connected to any real hardware, but rather emulates its behavior.
>>
>> The dummy DMA buffer is meant to be used as a template for implementing DMA
>> buffer support and can also be used to test the generic IIO DMA buffer
>> infrastructure without having access to hardware that has DMA capabilities.
>>
>> The dummy driver is split into two parts. The first part emulates the
>> behavior of a typical DMA controller and converter while the second part
>> implement a typical device driver for such a system. The separation of the
>> two parts is intentionally kept very strict to be to make it clear which
>> parts will be found in a driver for real hardware and which parts will be
>> performed by the hardware and will not be part of the driver.
>>
>> The type of the buffer used by the IIO dummy device has to be chosen at
>> compile time and can either be the old FIFO based software triggered buffer
>> or the DMA buffer. Given that the dummy device driver is mainly intended
>> for testing the framework and providing a simple example to be used as a
>> template for new drivers it is not critical that the buffer type can be
>> chosen or changed at runtime.
> I almost wonder if it's worth building two modules. One with the kfifo and
> one with the dma buffer.
> 
> This is mainly to avoid confusing the distros who will wonder which
> 'fake' option to chose.

Ideally distros shouldn't ship this at all. But we could allow to built both
and then use a module parameter to choose which one to use when both are
built into the module.