Accelerometer problem

Timo Drick timo at drick.de
Sat Jul 12 16:15:59 CEST 2008


Andy Green schrieb:
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> 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.
>
> 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.
>
> - -Andy

Hi Andy,

if i shutdown X-Server i am able to open the /dev/input/events twice or 
more times. And it work. So it should be not the problem if the device 
is opened by multiple processes. Just if the X-Server is up only one 
event work. lsof show that all events are opened by neod:
 >lsof
neod      1675          root    4r   CHR      13,64               1427 
/dev/input/event0
neod      1675          root    6r   CHR      13,65               1568 
/dev/input/event1
neod      1675          root    7r   CHR      13,66               1590 
/dev/input/event2
neod      1675          root    8r   CHR      13,67               1609 
/dev/input/event3
neod      1675          root    9r   CHR      13,68               1464 
/dev/input/event4


-- Timo



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