Accelerometer problem

Marcus Bauer marcus.bauer at
Thu Jul 10 12:05:25 CEST 2008

On Thu, 2008-07-10 at 10:56 +0100, Andy Green wrote:
> Hash: SHA1
> Somebody in the thread at some point said:
> | On the OM2007.2 images it is the neod which opens the accelerometers. No
> | reason for doing so, even more as neod starts to eat 50% CPU, because
> | the am's send both 100 events per second...
> |
> | If anybody is interested, I recompiled the neod without this and without
> | the click-sound. Drop me a mail.
> |
> | No more probs with the am's and everything a lot faster.
> Well I am glad to hear it can be made stable, because I did believe I
> fixed the instability last patch set.

Just for adding more information: I used one of the lastest builds from
the openmoko repository and the accelerometer was running for two days
using a slightly modified version of Thomas Wood's which reads
them every 100ms. Usually it ran for a couple of minutes before getting
stuck reading /dev/input/event3. Once was killed the output of
cat /dev/input/event3 remained empty until a reboot. Now it works.

> However I don't get why neod sucking on the input device too makes
> trouble (other than the CPU load or whatever).  The input layer in Linux
> takes care about copying the input content around consistently so
> everyone with the input device open gets one copy of what's happening.
> Ie, the accel driver is not aware that there are multiple apps
> listening.  I guess it is a bug in the accel driver somehow still, but a
> much less worrying one that the SPI sharing difficulties until now.


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