GPS rework: Please test and report on software fix prior to attempting any hardware fix

[Al Johnson]

On Tuesday 05 August 2008, Michael Shiloh wrote:
> Agreed. I've been trying to gather that information for the past little
> while. It's proven rather elusive, and I didn't want more people to try
> the hardware fix until we really understand what the software fix can
> do, so I thought I'd better ask for the test ASAP, and then continue
> working on the info.
>
> Andy, can you provide links to two kernels: one before, and one after
> the fix?

IIRC the first kernel to have the sd_drive and sd_idleclk fixes in was from 
20080723, but this seems to have been removed from the buildhost now. Or did 
you mean the fix to slow down the SD clock while GPS is enabled that was 
added Friday? In either case I think t can be configured to behave as it did 
before the fix by echoing the right variables into /sys/wherever and 
accessing the SD card.

> The test will consist something like
>
> cat /dev/ttySAC1 | grep GPGGA
>
> and then time it until it gets a fix. I'll be more specific.

For a bit more consistency of timing, less manual intervention, and enough 
readings to get an idea of the run to run variation in that location, can I 
suggest a script? It could do with a timeout when waiting for a fix since 
with deivestrength 3 and idleclk 1 this can take a _very_ long time, possibly 
forever in some locations!

#!/bin/sh
PASSES=10
TTFF=""

get_ttf() {
  echo "1" > /sys/bus/platform/devices/neo1973-pm-gps.0/pwron
  TTFF=`(time grep "GPRMC,[0-9\.]*,A," -m 1 /dev/ttySAC1) 2>&1 |grep real`
  echo "0" > /sys/bus/platform/devices/neo1973-pm-gps.0/pwron
  echo $DRIVESTRENGTH $IDLECLK $TTFF
  sleep 20
}

echo d i time
until [ $PASSES -eq 0 ]
do
  for DRIVESTRENGTH in 0 1 2 3
  do
    for IDLECLK in 0 1
    do
      #echo testing drive strength $DRIVESTRENGTH and clock idle $IDLECLK
      echo $DRIVESTRENGTH > /sys/module/glamo_mci/parameters/sd_drive
      echo $IDLECLK > /sys/module/glamo_mci/parameters/sd_idleclk
      touch /media/card/gpstest
      sync
      get_ttf
    done
  done
  PASSES=$(($PASSES-1))
done

> Perhaps I'll set up a wiki page for this.
>
> Michael
>
> Josh Thompson wrote:
> > Could we get a link to some image files to use for this testing?  I'm not
> > quite sure when Andy's fix made it in the kernel.  It would also help
> > standardize the tests if we all use the same images.
> >
> > Josh
> >
> > On Mon August 4 2008 7:29:17 pm Michael Shiloh wrote:
> >> Before we conclude that the hardware fix is required, we'd really like
> >> to gather a lot of statistics from you about the behavior of the
> >> software fix. We have been able to test in only a limited number of
> >> locations, and a limited number of phones.
> >>
> >> We'd like to ask you to run some tests and report back the TTFF in each
> >> case:
> >>
> >> 1. Prior to Andy's software fix
> >> 1a. Without SD card
> >> 1b. With SD card
> >>
> >> 2. Using Andy's software fix
> >> 2a. Without SD card
> >> 2b. With SD card
> >>
> >> Preferably run this test in multiple locations.
> >>
> >> Results should be reported on a wiki page, which should include your
> >> location (so we can assess other influences e.g. satellite elevation and
> >> weather conditions)
> >>
> >> Thanks,
> >> Michael
> >
> > _______________________________________________
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>
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