[SHR-Unstable] Forcing fast-charge

Joerg Reisenweber joerg at openmoko.org
Sat May 2 03:30:10 CEST 2009

Am Mi  29. April 2009 schrieb Cédric Berger:
> On Tue, Apr 28, 2009 at 15:36, Joerg Reisenweber <joerg at openmoko.org> wrote:
> >
> > That's nonsense as there is no dumb charger out there not being capable of
> > supplying 500mA. OTOH any management of maximum ingress current to USB by
> > whatever means will inevitably fail when unplugging the charger device
> > connected to FR during powerdown and replace it with a (nonexistent) 
> > one.
> And what if the "charger" is a small usb host device... like a Freerunner ?
Then uBoot should do standard USB enum. Which is negotiating current host is 
able to deliver.

> Or a solar panel ?
How could setting BAT_CURLIM to USB_CURLIM help?

> Or you have 2 phone charging from the same usb port ?
or I'm using the usb extension in my usb-coffemug-warmer? Or create a 
shortcircuit? It's not a valid usecase and I don't see how to accomplish 

> I usually charge from a car charger and when I want to charge faster than
> 500mA from usb (so ~300mA to battery with phone on), I have to push usb
> limit to 1A.
No you have to push USB_CURLIM to >500mA, if you want >500mA.

> But as it is too much for my poor charger, I also limit battery charge
> current (ex 500mA).
How could setting BAT_CURLIM to USB_CURLIM help?

> This way I have about 700-750mA pulled from my charger (though it can peak
> to 1A as needed).
What's the rationale behind that?
If you set USB_CURLIM to 750mA you get exactly the same behaviour without the 
useless "when needed" part.
How could setting BAT_CURLIM to USB_CURLIM help?

> Note than doing this (I used a little GUI with 1 set button for each value),
> I must set usb current limit, then only I set charge current limit. And in
> the meanwhile, since charge limit=usb limit=1A, it starts pulling about 1A
> and I cannot avoid that.
Sorry I don't understand this statement.

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