Re: Kernel wishlist item: Better IIO API

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

On 10/29/2014 06:33 PM, Bastien Nocera wrote:
> On Wed, 2014-10-29 at 18:21 +0100, Lars-Peter Clausen wrote:
>> On 10/29/2014 03:30 PM, Bastien Nocera wrote:
>>> Hey,
>>>
>>> I've posted this a couple of days ago:
>>> http://www.hadess.net/2014/10/a-gnome-kernel-wishlist.html
>>> along with a mail to LKML:
>>> http://thread.gmane.org/gmane.linux.kernel/1810083
>>>
>>> I've recently added to my list an item about IIO:
>>> https://wiki.gnome.org/BastienNocera/KernelWishlist
>>>
>>> Are there any plans for a better API for the IIO subsystem? The API
>>> might be good enough to drive from shell scripts, or helpers that only
>>> need to work with one variant of a device, but my attempts at trying to
>>> use the IIO subsystem to provide an accelerometer to do automatic
>>> display rotation[1] showed that the API is really cumbersome.
>>>
>>> The code I wrote spends most of its time creating sysfs paths, reading
>>> values in different formats, and mangling filenames[2].
>>>
>>> Is an ioctl-based API planned? Something where I could get/set
>>> structures to gather metadata about the device, and set it up easily, so
>>> reading data from it is easier?
>>
>> No, unfortunately not and I'm not sure if such a ABI would be accepted if
>> proposed.
>
> Why not?

Because it means there will be ambiguity in the API on how to do things. 
Which is typically not a desired property.

>
>> But checkout libiio[1][2], it hides the details of the sysfs file manipulation.
>
> I'm not sure that's any better unfortunately. I've certainly tried to do
> that already in my code, but that doesn't change that the user-space API
> is barely usable.

It's not completely unusable ;)

- Lars