linux-kernel - Re: Motorola Droid 4 progress, power consumption

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Date:   Wed, 2 May 2018 21:10:49 +0200
From:   Pavel Machek <pavel@....cz>
To:     Tony Lindgren <tony@...mide.com>
Cc:     kernel list <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-omap@...r.kernel.org, sre@...nel.org, nekit1000@...il.com,
        mpartap@....net, merlijn@...zup.org
Subject: Re: Motorola Droid 4 progress, power consumption

Hi!

> > Anyway, >5.5hours of standby with screen off, GSM on is already
> > usable.
> 
> Just to rub that in, you do mean GSM usable for voice calls and
> SMS with your unicsy_demo with mainline kernel plus the pending
> LCD related patches, right? :)

Plus some other patches, yes.

> > This is the core of code I'm using.
> > 
> > https://github.com/pavelmachek/unicsy_demo
> > 
> > Battery graphs are attached. I'm not sure if the battery was really
> > close to empty at that point -- voltage curve should have different
> > shape if that was the case. 
> 
> Cool. BTW, the value for POWER_SUPPLY_POWER_AVG should be quite
> accurate for the whole device power consumption.

Aha, I was looking in the wrong directory. Yes, these look useful.

> It comes from the shunt resistor measured by the PMIC. Sorry I don't
> remember how often it needs to be polled but I'm guessing polling it
> once a minute or so should be plenty.

Ok. I normally do once in 30 seconds.

> Hmm oh and the POWER_SUPPLY_CHARGE_COUNTER value should be monitored
> by your libbattery and it's low value and high value should be saved
> to a file. Low should be saved when we get the battery low interrupt
> and battery state changes to POWER_SUPPLY_CAPACITY_LEVEL_CRITICAL.
> High value should be saved on POWER_SUPPLY_CAPACITY_LEVEL_FULL.
> 
> Then when you know the high value and low value, you can calculate
> the remaining capacity based on the current value and
> POWER_SUPPLY_POWER_AVG.

Ok, more stuff on TODO list. I actually use python hacks, and not
libbattery now.

Is this one correct?

voltage_min_design:3100000

I believe you mentioned flash stops working at 3.3V. What is important
from my point of view is to shut the system down when the battery is
low. I believe that still needs to be implemented.

Is it appropriate to shutdown at POWER_SUPPLY_CAPACITY_LEVEL_CRITICAL?
But then libbattery will race with shutdown to save the thresholds...

I also have some hacks to allow configuration of the full
voltage. Charging to 4.35V is pretty agressive, and I believe baterry
will be damaged less if we only charge to 4.1V.

Best regards,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html