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

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Date:	Fri, 21 Nov 2014 15:37:10 -0800
From:	Tony Lindgren <tony@...mide.com>
To:	NeilBrown <neilb@...e.de>
Cc:	Felipe Balbi <balbi@...com>,
	"Dr. H. Nikolaus Schaller" <hns@...delico.com>,
	Grazvydas Ignotas <notasas@...il.com>,
	Igor Grinberg <grinberg@...pulab.co.il>,
	Lee Jones <lee.jones@...aro.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	List for communicating with real GTA04 owners 
	<gta04-owner@...delico.com>
Subject: Re: [PATCH] mfd: twl4030-power: Fix poweroff with PM configuration
 enabled

* NeilBrown <neilb@...e.de> [141118 19:45]:
> On Wed, 12 Nov 2014 16:31:54 -0600 Felipe Balbi <balbi@...com> 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.

Regards,

Tony
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