Re: [beagleboard] BBB Battery shutdown

Mike Mon, 18 Apr 2016 14:27:12 -0700

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 userswho might find this helpful. Currently the powerfail uses the same keyfunction as the pwr button, so the first place to start would bechanging the key function to something else. Also, the interruptroutine 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 aprogramming perspective...


Mike

On Apr 18, 2016, at 11:31 AM, William Hermans <[email protected]<mailto:[email protected]>> wrote:


#1
william@beaglebone:~$ ls /etc/udev/rules.d/

50-hidraw.rules 50-spi.rules 60-omap-tty.rules70-persistent-net.rules uio.rules

#2

We do not care about the button press. We *did* care about whathappens 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 muchhassle for a result that is not really all that important. So what ifthe power down routine is inefficient . . . it works.

On Mon, Apr 18, 2016 at 10:29 AM, John Syne <[email protected]<mailto:[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]
    <mailto:[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] <mailto:[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] <mailto:[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

        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] <mailto:[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] <mailto:[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.



        
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