Re: [PATCH] mfd: twl4030-power: Fix poweroff with PM configuration enabled

From: Tony Lindgren
Date: Fri Nov 21 2014 - 18:37:35 EST

* NeilBrown <neilb@xxxxxxx> [141118 19:45]:
> On Wed, 12 Nov 2014 16:31:54 -0600 Felipe Balbi <balbi@xxxxxx> wrote:
> >
> > this is actually what the USB Battery Charging spec requires us to
> > implement. If Linux is doing differently, it's a bug on Linux which
> > should be fixed :-)
> >
> > No host is allowed to source more then one unit load (100mA in LS/FS/HS,
> > 150mA in SS) until the device is fully enumerated. Host are also
> > required to drop max current budget to 8mA (IIRC) if the device doesn't
> > enumerate for however many minutes (I guess it was a pretty long
> > threshold, something like half an hour or so. My memory fails me right
> > now).
> >
> I think the twl4030 driver does do the "right" thing unless the "allow_usb"
> module parameter is set, in which case it enables charging at a higher rate
> which is 600mA (default value of BCIIREF1).
> It would be nice if the driver could check if a charger was plugged in and
> act accordingly.
> The charger I have for my openmoko is identified by a 47K resistor between ID
> and ground. The twl4030 can detect that easily enough, but it isn't very
> standard.

Sounds doable to me, feel free to patch it up since you guys are using
the twl4030 charger :)

> The standard is of course to have D+ and D- shorted, but I don't know if the
> twl4030 can detect that? If it can, then getting some very early code to
> check for the short (or the 47k resistor) and quickly enabling charging might
> be a sufficient solution.

I guess. Note that there's also the USB BC1.2 spec that is more
complicated than having the data lines shorted.


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