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Re: [PATCH] IDE: Fix platform device registration in Swarm IDE driver

To: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Subject: Re: [PATCH] IDE: Fix platform device registration in Swarm IDE driver
From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Sun, 28 Sep 2008 19:18:36 +0200 (CEST)
Cc: Ralf Baechle <ralf@linux-mips.org>, bzolnier@gmail.com, linux-ide@vger.kernel.org, "Maciej W. Rozycki" <macro@linux-mips.org>, linux-mips@linux-mips.org
In-reply-to: <48DF7DBC.1080804@ru.mvista.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20080922122853.GA15210@linux-mips.org> <48DA1F9D.6000501@ru.mvista.com> <20080928114711.GB9207@linux-mips.org> <48DF7DBC.1080804@ru.mvista.com>
Sender: linux-mips-bounce@linux-mips.org
On Sun, 28 Sep 2008, Sergei Shtylyov wrote:
> Ralf Baechle wrote:
> 
> > > > +{
> 
> > > [...]
> 
> > > > +       pdev = platform_device_register_simple(DEV_NAME, -1,
> > > > +                      swarm_ide_resource, 
> > > > ARRAY_SIZE(swarm_ide_resource));
> 
> > >  If you have the resources as static array anyway, why not have the
> > > device in the static variable too and use platform_device_register()?
> 
> > It saves a few lines of code.
> 
>    And wastes few words of static data since platform_device_register_simple()
> will kmalloc() the resources and do a copy from these resources after which
> they are not needed -- so, it's worth making swarm_ide_resource[] __initdata
> at least.
>    If you were using platform_device_register() with static platform device,
> no memory allocation would have happened, and no data would have been wasted.

Indeed, there are different static/dynamic memory usage patterns for the
various ways to register platform devices. Unfortunately (AFAIK) it's not
properly documented which to use when.

E.g. if some devices may be present (as indicated by e.g. firmware),
which one is the most optimal to use?

Gr{oetje,eeting}s,

                                                Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                                            -- Linus Torvalds

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