FSO 2.6.28 usage report

Stefan Schmidt stefan at openmoko.org
Mon Jan 12 19:41:09 CET 2009


On Mon, 2009-01-12 at 17:47, Simon Kagstrom wrote:
> On Mon, 12 Jan 2009 14:33:00 +0100
> Stefan Schmidt <stefan at openmoko.org> wrote:
> > > | Threshold for accels. We finally like to ship the great accel
> > > | gesture application from our GSoC student, but it would only be
> > > | really useful if we could set a threshold instead of parsing 
> > > | data all the time and burn cpu.
> > >
> > > This is done by Simon Kagstrom some time ago, it's down in /sys.
> > > Maybe Simon can give some advice.
> >
> > Cool, that must have slipped through our radar. Simon, is the
> > threshold working and if how can we use it?
> I sneaked it in low under the radar at the kernel mailing list ~two
> months ago or so :-)


> It's simple to use, just write the threshold value in mg's
> to /sys/.../lis302dl.1/threshold. Writing zero will revert to the
> default behavior and generate each data item. To get a feeling of how
> it works, just hexdump the accelerometer input device and raise the
> threshold until the device no longer generates data when lying still on
> the table.

OK, cool. That should give us enough input to work it out in userspace.

> In the long run, I think an adaptive daemon could be used to export the
> accelerometer data with thresholds. The threshold can be a slight
> problem if the user use slow, smooth moves (although I think the
> duration parameter can help with that).
> So I think the daemon could set the threshold high at start, wake up
> when the user starts moving around the phone and set the threshold to
> zero until the device stops moving.

Hmm, interesting approach. We should discuss about this once we have fso MS5
out. Hopefully in February we can go in hack-and-break mode again. :)

> The issue of users walking around with the phone with
> accelerometer-dependent apps is ... an interesting problem.

Indeed. Thanks for the kernel work on this.

BTW, what was the last word on wakeup from the accels? With a god threshold this
could be nice. :)

Stefan Schmidt

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