Also, I think ideally, if you need to retain USB during power outages, you
would be better off making, or buying a UPS, and using that instead of an
on board battery.

On Tue, Apr 19, 2016 at 3:30 PM, William Hermans <[email protected]> wrote:

> So there is apparently a bug related to this whole situation. Once the
> input power goes away, whatever it may be. You lose USB, because the PMIC
> is not longer able to supply 5V. You even get a kernel message in relation
> to this from musb.
>
> The problem is, once input power is restored, I see no indication that 5V
> is restored to USB. So If you tail -f /var/log/messages, you'll see one
> musb message when pulling power, but you will not see a corresponding
> message when plugging power back in. Additionally if you pull power
> multiple times. Only the first message is displayed.
>
> What this tells me is that the current kernel modules are not written to
> deal / handle this yet. So for now, unless I'm wrong ( which i doubt ).
> It's best just to power down period. After input power goes away, and
> simply use an R/C network to "time" system up's, in case power goes up /
> down rapidly. One, or more times consecutively.
>
> On Mon, Apr 18, 2016 at 6:26 PM, William Hermans <[email protected]>
> wrote:
>
>> *I have an interest in this.  It's way above my pay grade from a
>>> programming perspective...*
>>>
>>> * Mike*
>>>
>>
>> Hi Mike,
>>
>> This is actually something I'm personally very interested in too.
>> However, at this moment in time, my buddy and I are actually in the process
>> of making two different capes for the beaglebone. So this is one of those
>> situations where you have to have priorities . . . and while I obviously do
>> not know everything involved to get this certain thing done, it is not
>> above my pay grade.
>>
>> So perhaps in the future, it may be something I'll revisit, and would be
>> something I'd contribute back to the community.
>>
>> On Mon, Apr 18, 2016 at 2:26 PM, Mike <[email protected]> wrote:
>>
>>> On 04/18/2016 03:31 PM, John Syne wrote:
>>>
>>> That is OK if this doesn’t work for you, but there are other BBB users
>>> who might find this helpful. Currently the powerfail uses the same key
>>> function as the pwr button, so the first place to start would be changing
>>> the key function to something else. Also, the interrupt routine does not
>>> report power good, so that would have to be added. After that, a systemd
>>> service could take care of the rest.
>>>
>>> Regards,
>>> John
>>>
>>>
>>>
>>> I have an interest in this.  It's way above my pay grade from a
>>> programming perspective...
>>>
>>> Mike
>>>
>>>
>>>
>>> On Apr 18, 2016, at 11:31 AM, William Hermans <[email protected]> wrote:
>>>
>>> #1
>>> william@beaglebone:~$ ls /etc/udev/rules.d/
>>> 50-hidraw.rules  50-spi.rules  60-omap-tty.rules
>>> 70-persistent-net.rules  uio.rules
>>>
>>> #2
>>> We do not care about the button press. We *did* care about what happens
>>> when power is removed, while a battery is connected.
>>>
>>> Now we do not care. We're not going to bother with it. It's too much
>>> hassle for a result that is not really all that important. So what if the
>>> power down routine is inefficient . . . it works.
>>>
>>> On Mon, Apr 18, 2016 at 10:29 AM, John Syne < <[email protected]>
>>> [email protected]> wrote:
>>>
>>>> I asked Robert how the pwr button is processed and interestingly it is
>>>> done via udev and systemd. Also, there is some new code going mainstream
>>>> for the pwr button and battery charger. Perhaps you can implement the timer
>>>> delay via a custom systemd service. Here is what Robert sent me:
>>>>
>>>> Oh this is finally getting upstreamed:
>>>>
>>>> https://www.spinics.net/lists/linux-omap/msg127184.html
>>>>
>>>> I need to switch to their version, vs our 3.8.13 erra hack that's been
>>>> forward ported for years. ;)
>>>>
>>>> Behind the scenes's that patch is reporting a key-event to systemd...
>>>>
>>>>
>>>> https://github.com/systemd/systemd/blob/09541e49ebd17b41482e447dd8194942f39788c0/src/login/70-power-switch.rules#L13
>>>>
>>>> Regards,
>>>> John
>>>>
>>>>
>>>>
>>>>
>>>> On Apr 17, 2016, at 11:06 PM, William Hermans < <[email protected]>
>>>> [email protected]> wrote:
>>>>
>>>> There is no timer in that code. The timer would have to be added, and
>>>> careful consideration would have to be given to exactly how that was
>>>> implemented.
>>>>
>>>> So in other words, you would, or should write a completely new kernel
>>>> module, that is meant to replace what already exists - As an option.
>>>>
>>>> On Sun, Apr 17, 2016 at 10:25 PM, evilwulfie < <[email protected]>
>>>> [email protected]> wrote:
>>>>
>>>>> Where in the code do you set that timer ?
>>>>>
>>>>>
>>>>>
>>>>> On 4/17/2016 7:50 PM, John Syne wrote:
>>>>>
>>>>> One more thing, the power down sequence uses the RTC framework
>>>>> (described earlier in this thread), so it will be possible to set a timer
>>>>> for the shutdown and the wait for the power to return event to cancel the
>>>>> timer. If the power on event does not occur, the shutdown will occur.
>>>>>
>>>>> Regards,
>>>>> John
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Apr 17, 2016, at 7:18 PM, evilwulfie < <[email protected]>
>>>>> [email protected]> wrote:
>>>>>
>>>>> Interesting.  Too bad if you want the battery to act as a UPS it cant
>>>>> some how notify the kernel that AC has been removed
>>>>> and have a routine to just chill a while to see if power comes back.
>>>>>
>>>>> Be nice to have a variable that is user settable for the time between
>>>>> loss of AC and shutdown.
>>>>>
>>>>> As it is now it sees the AC removed, shuts down and no easy way to
>>>>> restart on power restored. Requiring some other IC to monitor power
>>>>> and then press the pwr_but to restart the processor.
>>>>>
>>>>>
>>>>>
>>>>> On 4/17/2016 7:10 PM, John Syne wrote:
>>>>>
>>>>> Yep, it is in the BB kernel:
>>>>>
>>>>>
>>>>> <https://github.com/RobertCNelson/bb-kernel/blob/am33x-v4.1/patches/beaglebone/dts/0006-tps65217-Enable-KEY_POWER-press-on-AC-loss-PWR_BUT.patch>
>>>>> https://github.com/RobertCNelson/bb-kernel/blob/am33x-v4.1/patches/beaglebone/dts/0006-tps65217-Enable-KEY_POWER-press-on-AC-loss-PWR_BUT.patch
>>>>>
>>>>> So again, on line 164 is the Interrupt routing. It is this line:
>>>>>
>>>>> + input_report_key(tps->pwr_but, KEY_POWER,
>>>>>
>>>>> + ~status_reg & TPS65217_STATUS_ACPWR);
>>>>> that send a power button pressed as an input key when the AC 5V power
>>>>> is removed.
>>>>>
>>>>> Regards,
>>>>> John
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Apr 17, 2016, at 4:52 PM, William Hermans < <[email protected]>
>>>>> [email protected]> wrote:
>>>>>
>>>>> The real reason why our source trees do not match up. My source tree
>>>>> is based on 4.1.x, and yours seems to be 3.8.x. The patch you showed above
>>>>> would probably botch up my source tree . . .
>>>>>
>>>>> On Sun, Apr 17, 2016 at 4:33 PM, William Hermans < <[email protected]>
>>>>> [email protected]> wrote:
>>>>>
>>>>>> Yeah I recognize that code from source code not written by TI
>>>>>> employees. The file is called tps65217_charger.c, and is written by an
>>>>>> employee of another company.
>>>>>>
>>>>>> Anyway, I think we're going to blow this off. The idea was to wait
>>>>>> around without power for 5 minutes, to see if power comes back up. Before
>>>>>> issuing a shutdown. Then, on the power up end, using a simple R/C circuit
>>>>>> to ramp up voltage to 5v over a specific time period.
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> <https://www.avast.com/en-us/lp-safe-emailing-2109?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient&utm_term=oa-2109-v2-a>
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>>>>>
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>>>>> www.avast.com
>>>>>
>>>>> --
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>>>>
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>>
>>
>

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