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

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Date:   Wed, 2 May 2018 07:41:58 -0700
From:   Tony Lindgren <tony@...mide.com>
To:     Pavel Machek <pavel@....cz>
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

* Pavel Machek <pavel@....cz> [180501 18:33]:
> Hi!
> 
> 4.17-rc1 is quite usable on droid 4; basically everything
> works. OHCI is running all the time, which means we burn a lot of
> power needlessly.

To work around that we can use n_gsm and and then suspend USB
device. That will need the modem wake gpio working that I'll
be sending patches for at some point.

And we should make cdc_wdm, qcaux and ohci support runtime PM
for autosuspend at some point. For *hci, we can make it work
along what Roger did in his earlier series here except by using
Linux generic wakeirq support:

https://lkml.org/lkml/2013/7/10/355

> 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? :)

> 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.

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.

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.

Regards,

Tony