Reason for GPS problems found!

Roland Mas lolando at
Sat Jul 19 16:39:12 CEST 2008

Timo Jyrinki, 2008-07-18 13:42:02 +0300 :

>>> Does anyone else have a reliability problem now with the new
>>> kernel and GPS when SD card is used?

Am Fr  18. Juli 2008 schrieb Roland Mas:

>> I have.  Didn't manage to properly isolate the problem, but my gut
>> feeling is that Andy's patch to disable SD when acquiring the first
>> fix does only that for, well, the first fix.  *Apparently*, there are
>> circumstances where running agpsgui once, getting a fix, exiting and
>> restarting afterwards, doesn't result in the FR getting a new fix.  As
>> you said, rebooting solves the problem, but suspend/resume cycles
>> don't seem to reliably fix it.

Joerg Reisenweber, 2008-07-19 00:26:14 +0200 :

> Sorry! There's *no* disabling of SDcard for FF! 

  My apologies.  I was under the impression that the gist of the
kernel patch was to temporarily switch off the clock for the SD card
reader when it's not in use, and that this was able to reduce
interference with GPS signals, thus helping TTFF.  But I haven't
touched radio comms for years, so I might be completely off.

> Who's talking about suspend/resume cycles, did I miss sth?

  I am.  Since rebooting seemed to have an influence on the problem, I
thought it could help if I tried suspending and report my results.

> Please read the appropriate posts describing the way this patch
> works.  Otherwise, please don't conclude on false assumptions, but
> just report what you observed. Thanks for regarding this, helps a
> lot!

  That's what I was trying to do.  I suppose my wording was not good
enough, and I apologise for that.

Roland Mas

Bee There Orr Bee A Rectangular Thyng!
  -- in Soul Music (Terry Pratchett)

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