linux-kernel - Re: [RFC/PATCH 1/5] usb: otg: add notifier support

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Message-ID: <20100126185026.GB20049@nokia.com>
Date:	Tue, 26 Jan 2010 20:50:26 +0200
From:	Felipe Balbi <felipe.balbi@...ia.com>
To:	ext David Brownell <david-b@...bell.net>
Cc:	"Balbi Felipe (Nokia-D/Helsinki)" <felipe.balbi@...ia.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Anton Vorontsov <avorontsov@...mvista.com>,
	Grazvydas Ignotas <notasas@...il.com>,
	Madhusudhan Chikkature <madhu.cr@...com>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: Re: [RFC/PATCH 1/5] usb: otg: add notifier support

On Tue, Jan 26, 2010 at 04:21:28PM +0100, ext David Brownell wrote:
>On Tuesday 26 January 2010, Felipe Balbi wrote:
>> >
>> >Thing is, supplying current is a bit more involved.  If the
>> >board can't supply 300 mA, the USB configuration selection
>> >mechanism has to know that, so it never selects peripheral
>> >configurations which require that much current.
>>
>> but that's done already by the usb core, no ? It rules out configuration
>> based on the hub->power_budget (can't remember if the field is that
>> exact name).
>
>Yes, it handles that ... but where does the power budget
>come from?  That's what I meant by "more involved".

we set it from board-files (on ARM, at least). It's a board 
characteristic, no ?

>As in, the host/supplying side of the power equation can't
>be event driven like the peripheral/consuming side can.
>
>And that's another reason I think it's best to fully solve
>the common (peripheral, recharge-that-batter) case first.

fair enough.

-- 
balbi
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