[PATCH 0/4] More SD / GPS noise reduction
sears at cs.berkeley.edu
Thu Jul 31 19:24:24 CEST 2008
The buzzing that I hear during phone calls has noticeably changed
character and gotten quieter since the last round of sd fixes went in.
It seems to happen more often before, and used to sound like continuous
GSM radio buzz. Now it's just a periodic "click click click" 10-100
times a second. Don't know how its changed things for people on the
other end of the call. Also, I don't make many phone calls, so I could
have just gotten lucky recently.
I have a question about reducing the sd card clock. sd access is done
without DMA, right? Doesn't that mean that slow factor 8 increases the
cpu cost of reading data from SD by 8x?
Andy Green wrote:
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> Somebody in the thread at some point said:
> | Andy Green wrote:
> |> - use the minimum negotiated voltage for the SD Card,
> | Nice !
> |> - when the GPS unit is powered, we dynamically reduce the
> |> clock rate to the SD Card.
> | Hmm, so are we still seeing GPS performance problems that this change
> | reduces ? I thought we had moved the bad frequency component(s) to a
> | safe enough place already ...
> Guy says it makes jitter for his tracking, other folks say it's not
> impacting them. Dunno, but these were "progress" anyway.
> Couple of guys say that WLAN on also jitters GPS tracking.
> - -Andy
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