[Gta04-owner] Linux 3.2-rc3 on GTA04

[NeilBrown]

On Sat, 26 Nov 2011 13:16:06 +0100 Christoph Mair <christoph.mair at gmail.com>
wrote:

> On Sat, Nov 26, 2011 at 12:43 PM, NeilBrown <neilb at suse.de> wrote:
> >  I have just updated
> >    git://neil.brown.name/gta04#merge
> >
> >  to 3.2-rc3.
> >
> >  Also in this release:
> >
> >  - Fixed the charging problem - I think [1]
> >  - We now charge the backup-battery.
> >  - Brand new driver for the LEDs (tca6507] [2]
> >  - Backlight control with PWM - untested [3]
> 
> Thank you for all the efforts! Cloning now...
> 
> > Future plans:
> >  - I want to look at the accelerometers as the next project.  Part of this is
> >   understanding the "iio" subsystem which seems to be the appropriate home.
> Or the input subsystem. There is already a bma150 driver in
> input/misc. The GTA04 uses the BMA180. They may behave similar..

Or maybe both.

The BMA150 does seem very similar to the BMA180.  It has a different set of
bandwidths and sensitivities but the important details are much the same.

However that driver doesn't do what I think is needed of an input driver at
all.

For me, the stream of x/y/z values (which is what that driver provides) is
largely uninteresting.
What I want to know is 
  when does the acceleration in any given direction change by more than Xg for
  at least Ysecs.
This allows the app to know when there has been a significant change in
orientation.
Also
  when was the device 'tapped' from any of the 6 directions.
which effectively provides 6 more hardware 'buttons'.


All of this is provided by the BMA1X0 hardware (and the lis302 hardware in
the freerunner) but the driver doesn't provide easy access to it.

So I imagine a driver that provides both an 'input' interface and an 'iio'
interface.
The 'input' interface that provides EV_KEY events of BTN_X BTN_Y BTN_Z on taps
and EV_ABS events of ABS_X ABS_Y ABS_Z whenever that has been a "sufficiently
large" change.

The 'iio' interface would provide the steam of x/y/z data and allow the
different trigger thresholds to be set.
The 'iio' interface can provide events somewhat similar to input but I don't
see the point of doing that when 'input' is already well-understood.
Thought maybe when I try I'll find out why...

NeilBrown
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