Re: [Ksummit-discuss] [TECH TOPIC] mobile phones

[Pavel Machek <pavel@ucw.cz>]

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Hi!

> > So to be exact... u-boot does not know about battery charging. And
> > NoLo can only do very, very slow charging.
> 
> Yes. The idea is, that normally NoLo only charges far enough, that
> Linux can be booted.
> 
> > Yes, unfortunately that does not work quite well here. Voltage goes
> > too low before Linux can boot, so it resets, but it is still high
> > enough for the bootloader, so it attempts to boot Linux one more time,
> > but battery is empty and voltage goes too low before Linux can boot, ...
> 
> I guess your battery is not the fittest anymore?

I guess that's one issue. (One of my batteries is actually so bad that
GSM modem fails with it.)

Well, I guess Debian boots a little longer than Maemo. Plus, I believe
we should charge the battery from kernel by default; it will enable
running fsck etc, and it will mean slow userspace boot will not
break...

> > > On N950 there is an unsupported gps connected via i2c iirc (with
> > > unknown protocol that needs to be RE'd) and TI's WiLink provides
> > > GPS on a shared UART link with bluetooth-style header using yet
> > > another protocol. I agree, that we should have a GPS subsystem.
> > 
> > Two GPSes in one box, interesting design. Are both of them connected
> > to useful antenna?
> 
> Actually there are probably 3 GPS implementations in Droid 4:
> 
>  * WL1285
>  * MDM6600 modem
>  * LTE modem
> 
> As far as I understand it modems are required to have GPS access in
> US. I'm not yet sure which of the implementations is used by Droid 4's
> stock system, but Motorola explicitly added a driver for the WL1285 GPS
> making it a likely candidate (The userspace part is a closed source
> shared object used by Android).

Interesting :-). I guess you could do really fair comparison of the
chipsets.

(Binary driver -- bad Motorola :-( )

> > +static int generic_protect(struct power_supply *psy)
> > +{
> > +	union power_supply_propval val;
> > +	int res;
> > +	int mV, mA, mOhm = 430, mVadj = 0;
> 
> 430 mOhm?

Yes, 0.43 Ohm.

> > +	if (mVadj < 3150)
> > +		shutdown("Battery internal voltage below 3.15V.");
> > +	
> > +	printk(KERN_INFO "Main battery %d mV, internal voltage %d mV\n",
> > +	       mV, mVadj);
> 
> s/internal voltage/open circuit voltage/g?

Will do.

Best regards,
									Pavel


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

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