linux-kernel - Re: Fundamental Design Flaw of the Device Driver Model?

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Message-ID: <20080822090318.GB6542@atrey.karlin.mff.cuni.cz>
Date:	Fri, 22 Aug 2008 11:03:18 +0200
From:	Pavel Machek <pavel@...e.cz>
To:	Eric Miao <eric.y.miao@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: Fundamental Design Flaw of the Device Driver Model?

> Fundamental Design Flaw of the Device Driver Model?
> ===================================================
> 
> Sorry for the misleading subject, its purpose is to draw your attention :-)
> The ideas below are preliminary and I hope I'm not making serious mistakes
> here.
> 
> This question has actually been around in my mind for several months, when
> I started to work on some devices with multiple functions. Specifically, a
> Power Management IC (PMIC in short in the following text) usually includes
> LEDs support (charging, indication...) audio, touch screen, power monitoring,
> LDOs, DC-DC bucks, and possibly some others.
> 
> The initial two ideas came into my mind were:
> 
>    1. separate the functions into multiple devices, write a driver for each
>       of these devices

Go for 1.

>    4. An intermediate device with no bus, no driver, no many other things
>       is really not something deserving a "struct device", that's a waste
>       of memory.

Memory is not _that_ expensive, and struct device is not that
big. Adding infrastructure to driver model for supporting this would
also cost you memory, this time in .text segment.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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