[PATCH 3/3] fix-lis302dl-dont-reset-hpf-each-time.patch

Andy Green andy at openmoko.com
Tue Feb 3 11:00:17 CET 2009


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Somebody in the thread at some point said:
| On Tue, 03 Feb 2009 09:42:54 +0000
| Andy Green <andy at openmoko.com> wrote:
|
|> We shouldn't be resetting the highpass filter every sample.
|>
|> It should be disabled if we don't use it or allowed to
|> work across multiple samples if we do.
|
| The threshold stuff needs this reset to work, but I suppose we could
| add a check if the threshold is actually set before resetting the HP
| filter. I don't think it affects "interrupt-on-every-datum" mode anyway.

What happens if we leave the HP filter un-reset with threshold?  It
sounds like it should only make it harder to reach the threshold, not
break things?

| While I don't have the data sheet available right now, I believe the
| LIS302DL_REG_FF_WU_SRC_1 is unrelated to the HP filter - I think it's
| an interrupt ack.

You're right the comment about reset HPF made it look like they're
related.  But that one too is only needed if there's a threshold wakeup.

- -Andy
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