Re: User-space API for accelerometer(s)?

[Bastien Nocera <hadess@hadess.net>]

Hey Peter,

On Wed, 2014-07-09 at 16:54 +0200, Peter Meerwald wrote:
> Hello Bastian,
> 
> > > We did also have a uinput based approach at one point but it was fairly clunky.
> > > That took data from iio buffers and pushed it back into the kernel via inputs
> > > userspace driver support. Not particularly nice but I thought I'd best mention
> > > it!
> > 
> > This is how I went in the end:
> > https://github.com/hadess/iio-sensor-proxy/
> > 
> > It's still far too resource hungry compared to the amount of work it's
> > doing (1 full percent of CPU!), and the rotation is too sensitive.
> 
> if I read the code correctly, prepare_output() configures the trigger, 
> enables the buffer, then performs one read, before undoing everything FOR 
> EACH SAMPLE

I based that code off Peter F. Patel-Schneider, and his yoga utilities,
and he probably got the idea from the generic_buffer.c example. It's not
clear what needs to be done there.

> this is probably not the way it should be done; I'd suggest to set up the 
> IIO buffer and then poll() or block on /dev/iio:deviceX -- however, this 
> uses the IIO device exclusively (might be an issue)

I've now pushed a version that will do the setup once, and open/close
the iio device when needed, in the timeout.
 The daemon still shows up in top, but I couldn't make it register
enough activity to show up in sysprof, so I'm guessing that top just
isn't measuring the CPU usage accurately.

I still have to fix the overeagerness to switch orientations, and I'll
be done for now I think.

Cheers