Re: Motorola Droid 4 progress, power consumption

From: Tony Lindgren <tony@atomide.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: kernel list <linux-kernel@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	linux-omap@vger.kernel.org, sre@kernel.org, nekit1000@gmail.com,
	mpartap@gmx.net, merlijn@wizzup.org
Subject: Re: Motorola Droid 4 progress, power consumption
Date: Wed, 2 May 2018 12:42:29 -0700	[thread overview]
Message-ID: <20180502194229.GM98604@atomide.com> (raw)
In-Reply-To: <20180502191049.ximiyccwfkjqcj7m@devuan>

* Pavel Machek <pavel@ucw.cz> [180502 19:12]:
> 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.

Cool :)

> > 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

Yes I think that's the voltage we get battery empty interrupt
and cpcap_battery_irq_thread() calls orderly_poweroff() shuts down
the device.

> 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.

The 3.3V case was for a different device, so the minimum level
can board specific and less than what the battery thinks it
might be.

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

No need to do anything except notify user at the battery
low interrupt CPCAP_BATTERY_IRQ_ACTION_BATTERY_LOW :)

> 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.

That should be based on the PMIC register values that Android
uses. Worth rechecking for sure, I thought it is higher than
normal too for the charge voltage.

Regards,

Tony