Date: Sat, 5 May 2007 16:32:30 +0400
From: Anton Vorontsov <cbou@mail.ru>
To: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Shem Multinymous <multinymous@gmail.com>, Greg KH <gregkh@suse.de>,
       linux-kernel@vger.kernel.org, kernel-discuss@handhelds.org,
       David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH 3/8] Universal power supply class (was: battery class)
Message-ID: <20070505123230.GA6460@zarina>
Reply-To: cbou@mail.ru
References: <20070503213139.GC20067@zarina> <41840b750705032155w21d98b5g6236daf9bff66606@mail.gmail.com> <20070505035413.GB21359@khazad-dum.debian.net>
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Hello Henrique, Shem,

On Sat, May 05, 2007 at 12:54:13AM -0300, Henrique de Moraes Holschuh wrote:
> On Fri, 04 May 2007, Shem Multinymous wrote:
> > >+enum power_supply_type {
> > >+       POWER_SUPPLY_TYPE_BATTERY = 0,
> > >+       POWER_SUPPLY_TYPE_UPS,
> > >+       POWER_SUPPLY_TYPE_AC,
> > >+       POWER_SUPPLY_TYPE_USB,
> > >+};
> > 
> > How about dumb (non-USB) DC power? Any reason to distinguish it from AC?
> 
> Hmm, if it should not be distinguished, it is better to rename AC to
> something that means continuous power.  But I'd rather have it AC and DC, as
> something might have both supplies separate, and you might want to
> differentiate them for some (human interface) reason.  After all, USB and DC
> are not really different anyway...
> 
> Anyway, what IS the difference between UPS and battery, or UPS and AC/DC for
> that matter?  When should UPS be used?  If you have UPS there, should not
> MGG (motor-generator group) also be provided?
> 
> Given that USB-power *is* usually also "dumb" (i.e. it doesn't do any
> control signaling over the USB bus for power-control purposes), IMHO it
> might be better to have just battery, AC and DC as types.  And a primary and
> secondary notion too, as that is common.  It would be generic.
> 
> Or maybe I just didn't get the idea behind the "type" attribute :-)
> 
> I'd appreciate if these were documented in the text file.

I think I got the start point of confusion. It's indeed bad to call such
power supply type as AC. Maybe I should it rename to ADAPTER? Or WALL?

type, is really `type' of power supply: imagine icon GUI application will
use for different types. Type is not alternating/direct current stuff,
it will be better to impelemnt `current_type' attribute for such matter.

As for Battery/UPS difference.. yes, they're quite similar.. but again,
imagine laptop with battery, and connected to UPS. ;-) How userspace
will differ internal battery from UPS? Yup, by type attribute. I hope
it makes sense... If not, we simply can remove UPS type.


And again, much thanks for your review and ideas!

-- 
Anton Vorontsov
email: cbou@mail.ru
backup email: ya-cbou@yandex.ru
irc://irc.freenode.org/bd2
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