From:  Terry <[email protected]>
Reply-To:  "[email protected]" <[email protected]>
Date:  Thursday, June 26, 2014 at 1:01 PM
To:  "[email protected]" <[email protected]>
Cc:  <[email protected]>
Subject:  [beagleboard] Re: Bone VDD_3V3EXP Disable Issues

> Does anyone know if there is a software solution to this issue?  I haven't
> seen any changes in the recent hardware revisions to address this.  We are
> currently planning on deploying a couple of dozen BBB and I would prefer not
> having to make hardware mods.
I¹ve just been looking into the PMIC for another user and this is probably a
configuration issue. The PMIC supports several modes (page 15 of the
TPS65217C datasheet). I believe the PMIC isn¹t configured to enter OFF mode,
but rather it is entering SLEEP mode which means any rails not controlled by
the power-down sequencer will remain enabled in SLEEP mode.

Here is what I think the solution might be:

Add "pmic-shutdown-controller" as shown in
/Documentation/devicetree/bindings/regulator/tps65217.txt.

In the V3.15.1-bone2 kernel, /drivers/mfd/tps65217.c line 213, the
comments ³Set the PMIC to shutdown on PWR_EN toggle². This should work for
all kernel V3.8 onwards.

Reading ³Power Down Sequence² on page 18 (TPS65217C datasheet), this will
initiate the power
down sequence and leave the PMIC in OFF mode.

I want to confirm this with Robert Nelson first before proceeding; however,
you can add "pmic-shutdown-controller² as described in the kernel docs to
/arch/arm/boot/dts/tps65217.dtsi and see if this works for you.

Regards,
John 

> 
> Terry
> 
> On Thursday, January 30, 2014 12:34:51 PM UTC-5, Brad Andersen wrote:
>> An update:
>> 
>> For the A6 (Beaglebone Black) version, I connected U4 pin 1 (enable) back to
>> VDD_3V3AUX (same as A5C).  It now shuts down correctly while on battery.
>> This was verified on two A6 BBB.
>> 
>> The mystery is what causes the VDD_3V3A to hang up on the A6 version when
>> shutting down while on battery.
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