andy git 06/15 suspend/resume observations

Joerg Reisenweber joerg at
Tue Jun 17 12:34:35 CEST 2008

Am Di  17. Juni 2008 schrieb Andy Green:
> Somebody in the thread at some point said:
> | Yes, I only get the pop now on resume.
> OK Great looks like we are working on the right issue.
> |> BTW Mark... we use the sideband path for voice data... no *ALSA* device
> |> is opened during that time, but we could do with 50K source impedence to
> |> Vref not 500K which happens shortly after you close an alsa device.  How
> |> do you think we should come at that?  Keep 50K up while there is any
> |> active analogue routing path open?  Or a new ALSA switch, or something
> |> else?
> |
> | In my application, I always have an *ALSA* device open when in a call. I
> | open different pseudo devices depending on the mode (normal with
> | speaker, normal in a call, speaker out in a call, headphone stuff, etc).
> Yes I don't think it makes any trouble here, it's just that solid Vref
> is still needed even if you are only using, say, a Mic input on an
> analogue path and not involving the CPU or Alsa at all.  It seemed like
> the driver currently believes it only has to maintain lower stability
> Vref if the CPU / PCM interface is not up, but that isn't true in the
> default rootfs case anyway.
> | I'll try to see if I can get it to happen with headphone jack. I can
> | also try disabling the radio interface to see if it will hang without a
> | GSM wakeup. Also keep in mind there is a long period of being in suspend
> | before an attempted resume. Make sure you give it 10 minutes or more
> | between suspend/resume.
> Wah I never really give it 10 minutes :-(  OK.  But this is going to be
> frustration hell.
> I also wonder what it is that counts out the 10 minutes to "know if it
> should go wrong".  Network timeouts from NFS external host?  The GSM
> chips are awake and can tell they didn't get talked to for 10 minutes?
> Waits for BATFULL somehow?  We turned a voltage rail off we shouldn't have?
> I guess with NFS rootfs you always have USB in during suspend, it might
> be interesting to see if the problem ever comes with local rootfs and no
> USB in during suspend.  If you want some tips on SD Card boot you're
> welcome.

Unexpected wake from suspend can be provoked by carrying around the device, 
*only* IF registered to GSM. So to me it's very clear some msg from GSM 
(probably associated to cell reselect or signal quality) is a source for 
unexpected wake. (OM-sw)

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