dont-smoke.patch (draw only 100mA in u-boot)

[joerg]

Am Di  25. März 2008 schrieb andrzej zaborowski:
> Hi,
> 
> On 09/03/2008, Andy Green <andy at openmoko.com> wrote:
> >  > This patch makes u-boot only draw up to 100mA from a USB port, unless
> >  > there's an indication that it can get more. I've also simplified the
> >  > code a bit.
> 
> I thought it might be useful for a user to manually provide such an
> indication if the user knows that the port provides 500mA but doesn't
> want her neo to do the full negotiation.  This indication could be a
> combination of the hw key events or something else.  I didn't get to
> implementing it yet.

I think i've seen a posting regarding a script or minimal app that's doing 
exactly this: writing some magic value to some /dev/*.
You can do this via udev too, for special hub etc


> > Why do we still have charging logic in U-Boot at all?
> >
> >  Are we planning on having charging logic in this minimal bootloader that
> >  is to replace U-Boot?
> 
> Actually that's not such a bad place for a minimal charging logic.
> Suppose your battery is completely flat and you want to charge as fast
> as possible, take the GPS and go on a trip.  As fast as possibly would
> be achieved by waking the cpu up for only a moment to tell the PMU to
> draw 500mA and powering-off.

There's no difference other than a few additional seconds to boot into full 
system, and then "switch off" again.
Charge logic in U-Boot doesn't help any better here.


> 
> The issue with running with no battery and risking damaging the
> upstream port (in the time between power-on and usb driver start)
> could be handled similarly: normally not supported but we would allow
> the user to say "do what I say" and boot on USB power.

How do you tell anything to NEO _prior_ to boot???
Power management should simply avoid drawing >100mA while booting (e.g. 
no/dimmed backlight, NO bat charging, no GSM/BT/WiFi etc).


cheers
jOERG