[Gta04-owner] Whose GTA04 think that battery is removed? Please report.

Andreas Kemnade andreas at kemnade.info
Wed May 3 17:15:03 CEST 2017


On Wed, 3 May 2017 13:05:59 +0200
"H. Nikolaus Schaller" <hns at goldelico.com> wrote:

> > Am 29.04.2017 um 21:03 schrieb Andreas Kemnade <andreas at kemnade.info>:
> > 
> > Hi,
> > 
> > my GTA04A5 thinks its battery is disconnected when it is suspended
> > while it is charging.
> > The Letux 3704 does not do that. Same kernels!
> > 
> > This phenomenom does only happen on the gta04a5 when the bit
> > WATCHDOGEN in BCIMFEN4 is enabled.
> > 
> > The bit is enabled by default. I am wondering whether this is a problem
> > related to the GTA04A5 hardware or my device.
> > 
> > Battery "disconnection" leads to immediate wakeup and charging stop.
> > 
> > Or the battery of the Letux3704 has stronger ties to the device so that
> > it cannot be disconnected by the kernel ;-)
> > 
> > Hmm, newer chip revision of the tps65950?
> I am not aware of. We used the same A3 variant. And the only significant change
> in the charging circuits is to use a different transistor. But that should not
> end in a battery-disconnect detection (maybe we should try to find out what
> situation does trigger that).
Well, as far as I understand even the bci does not detect a battery
disconnect directly. I disabled the corresponding bit in BCIMFEN4.
(BTW: There are some restrictions writing to that register, so read
back to check!) Still a battery "disconnection"
clearing WATCHDOGEN in that register inhibits that disconnection.
For some unknown reason that watchdog triggers (somehow trouble with
MADC). It resets the state machine of the charger. And as a side effect
there seems to be that disconnect.

So the key point is understanding
a) that watchdog.
b) access arbitation to madc.
  - maybe some measurement is started and not finished
    when it is suspended, but why this happens only on a5
    not a4?
c) madc power management
  - madc is enabled once but seems not to be disabled on suspend?
  - some other resource is disabled but needed by madc, but again why
    only on a5?

I even have a workaround patch in my tree which clears that WATCHDOGEN,
but I have not found a good place in code to do that because it is
enabled again at some unknown time. So it does not work properly.

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