From mboxrd@z Thu Jan  1 00:00:00 1970
Subject: Re: [PATCH v2] mtd: dataflash: add device tree probe support
From: Artem Bityutskiy <dedekind1@gmail.com>
To: Shawn Guo <shawn.guo@freescale.com>
Date: Wed, 20 Jul 2011 08:32:45 +0300
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Cc: patches@linaro.org, Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>,
	devicetree-discuss@lists.ozlabs.org,
	Grant Likely <grant.likely@secretlab.ca>,
	linux-mtd@lists.infradead.org, Shawn Guo <shawn.guo@linaro.org>,
	David Woodhouse <dwmw2@infradead.org>, linux-arm-kernel@lists.infradead.org
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On Wed, 2011-07-20 at 13:28 +0800, Shawn Guo wrote:
> On Wed, Jul 20, 2011 at 08:17:45AM +0300, Artem Bityutskiy wrote:
> > On Wed, 2011-07-20 at 12:55 +0800, Shawn Guo wrote:
> > > On Wed, Jul 20, 2011 at 07:40:38AM +0300, Artem Bityutskiy wrote:
> > > > On Fri, 2011-07-15 at 12:49 +0800, Shawn Guo wrote:
> > > > > > > +static const struct of_device_id dataflash_dt_ids[] = {
> > > > > > > +	{ .compatible = "atmel,at45xxx", },
> > > > > > > +	{ .compatible = "atmel,dataflash", },
> > > > > > > +	{ /* sentinel */ }
> > > > > > > +};
> > > > > > > +
> > > > > > 
> > > > > > This should be protected with a #ifdef CONFIG_OF/#else/#endif, and
> > > > > > there should be a MODULE_DEVICE_TABLE().
> > > > > > 
> > > > > I personally hate #ifdef stuff.  But okay, I can do it since there
> > > > > are people being concerned by this little waste of space.
> > > > 
> > > > I guess the question is - will it compile and work if CONFIG_OF is
> > > > unset?
> > > > 
> > > Yes, it will compile, as 'struct of_device_id' is defined in
> > > include/linux/mod_devicetable.h unconditionally.
> > 
> > And it will work correctly even though dataflash_dt_ids is not NULL, it
> > will not confuse MTD layer?
> > 
> I think for non-dt case, dataflash_dt_ids is not used anyway.  So yes,
> it will not confuse MTD layer, at least from my testing.

And it is not error-prone? I mean, it is not very likely that someone
changing MTD could make wrong assumptions and break dataflash driver? If
so, then we probably do not need ifdefs indeed.

-- 
Best Regards,
Artem Bityutskiy