linux-kernel - Re: Zaurus suspend saga

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Message-ID: <20090908211933.GB17228@elf.ucw.cz>
Date:	Tue, 8 Sep 2009 23:19:33 +0200
From:	Pavel Machek <pavel@....cz>
To:	Stanislav Brabec <utx@...guin.cz>
Cc:	Richard Purdie <rpurdie@...ys.net>, lenz@...wisc.edu,
	kernel list <linux-kernel@...r.kernel.org>,
	Dirk@...er-Online.de, arminlitzel@....de,
	Cyril Hrubis <metan@....cz>, thommycheck@...il.com,
	linux-arm-kernel <linux-arm-kernel@...ts.arm.linux.org.uk>,
	dbaryshkov@...il.com, omegamoon@...il.com, eric.miao@...vell.com,
	Andrea Adami <andrea.adami@...il.com>
Subject: Re: Zaurus suspend saga

Hi!

> > > c) We rip the whole thing out and stop supporting "offline" charging.
> > 
> > How much faster is offline charge, compared to online charging? I have
> > impression that online charging basically does not charge anything...
> 
> I think that online charging works, but it seems to be slower. I am not
> sure, whether it is a hardware or software issue. You can control
> charging speed by software, but the final word has the charging
> chip.

Well, overnight charge (online) seems to result in pretty much empty
battery...


> Here are control wires:
> SPITZ_SCP_JK_A: output = turns dummy load to 1 kOhm resistor
> SPITZ_SCP_JK_B: output = high charging current
> SPITZ_SCP_CHRG_ON: output = charging on
> SPITZ_SCP_ADC_TEMP_ON: output = turns battery sensor on/off
> SPITZ_GPIO_CHRG_FULL input = charging complete
> SPITZ_GPIO_AC_IN input = AC adapter is present

Is CHRG_ON pin reversed?

static void spitz_charge(int on)
{
	if (on) {
		if (sharpsl_pm.flags & SHARPSL_SUSPENDED) {
			gpio_set_value(SPITZ_GPIO_JK_B, 1);
			gpio_set_value(SPITZ_GPIO_CHRG_ON, 0);
		} else {
			gpio_set_value(SPITZ_GPIO_JK_B, 0);
			gpio_set_value(SPITZ_GPIO_CHRG_ON, 0);
		}
	} else {
		gpio_set_value(SPITZ_GPIO_JK_B, 0);
		gpio_set_value(SPITZ_GPIO_CHRG_ON, 1);
	}
}


> MAX1111 inputs:
> MAX1111_ACIN_VOLT: Voltage in AC input (after pass of input circuit,
>                    before tha final diode)
> MAX1111_BATT_TEMP: Battery temperature sensor
> MAX1111_BATT_VOLT: Battery voltage
> 
> Here are notes from the design:
> Pre-charge = 102mA

> Fast charge = 680mA
> Fast charge set ON = 105mA

I'm quite confused:

> SPITZ_SCP_JK_B: output = high charging current

Is JK_B active low?

> Iterm = 55mA
> 
> Thresholds:
> SPITZ_GPIO_AC_IN:     4.2V (IC charging circuit)
> SPITZ_GPIO_FATAL_BAT: 3.0V (voltage detector IC on battery)
> PXA270 batt fault:    2.8V (voltage on the main non-regulated power)
> CF/SD:                2.8V (voltage required for CF/SD activation, I am
>                             not sure, why it is done, because 2.8V is
>                             outside of spec anyway)

> - It would be nice to have "small travel charger heuristic": Turn fast
> charging on, charger "disappears", switch to slow charging, charger
> "appears" => stay in slow charging mode, and retry after some time, or
> after going to suspend, reset the flag when charger is removed.

Yes, I have similar "travel charger" (from single AA in fact), too,
and yes getting that heuristic would be cool. But for now, I'd settle
with /sys control enabling that.

> - sysfs interface for charging would be nice. For example: Cyril has an
> external battery pack and he wants to disable charging of internal
> battery from the external battery.

Yes, more debug info in sysfs and some controls would be nice.

BTW... /sys/class/leds/spitz:amber:charge seems to have life of its
own. I can't manually change the brightness; also changing trigger
does not work -- it still displays charging status. What is going on?

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