Re: [PATCH 1/3] ARM: OMAP2+: make of_device_ids const

From: Tony Lindgren <tony@atomide.com>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: devicetree@vger.kernel.org,
	Kevin Hilman <khilman@deeprootsystems.com>,
	Rajendra Nayak <rnayak@ti.com>, Rob Herring <robh+dt@kernel.org>,
	kernel@pengutronix.de, Grant Likely <grant.likely@linaro.org>,
	linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/3] ARM: OMAP2+: make of_device_ids const
Date: Thu, 11 Sep 2014 12:47:17 -0700	[thread overview]
Message-ID: <20140911194716.GG18849@atomide.com> (raw)
In-Reply-To: <20140911194215.GO3755@pengutronix.de>

* Uwe Kleine-König <u.kleine-koenig@pengutronix.de> [140911 12:42]:
> Hello Tony,
> 
> On Thu, Sep 11, 2014 at 12:14:50PM -0700, Tony Lindgren wrote:
> > * Uwe Kleine-König <u.kleine-koenig@pengutronix.de> [140911 12:02]:
> > > On Thu, Sep 11, 2014 at 10:39:43AM -0700, Tony Lindgren wrote:
> > > > * Uwe Kleine-König <u.kleine-koenig@pengutronix.de> [140910 01:27]:
> > > > > of_device_ids (i.e. compatible strings and the respective data) are not
> > > > > supposed to change at runtime. All functions working with of_device_ids
> > > > > provided by <linux/of.h> work with const of_device_ids. So mark the
> > > > > non-const function parameters and structs for OMAP2+ as const, too.
> > > > 
> > > > Hmm this does not seem to compile with omap2plus_defconfig because
> > > > of section type conflicts. Looks like there's some issue now with the
> > > > use of __initconst:
> > > > 
> > > > arch/arm/mach-omap2/board-generic.c:262:20: error: dra72x_boards_compat causes a section type conflict with omap_dt_match_table
> > > > arch/arm/mach-omap2/board-generic.c:30:34: note: ‘omap_dt_match_table’ was declared here
> > > > scripts/Makefile.build:257: recipe for target 'arch/arm/mach-omap2/board-generic.o' failed
> > > The problem is dra74x_boards_compat though:
> > > 
> > > 	static const char *dra74x_boards_compat[] __initconst = {
> > > 		...
> > > 
> > > *dra74x_boards_compat is const, but dra74x_boards_compat isn't, so
> > > either the variable must go into __initdata or it must be declared as:
> > > 
> > > 	static const char * const dra74x_boards_compat[] __initconst = {
> > > 		...
> > 
> > Ah OK.
> >  
> > > (but then I guess you get another warning because struct machine_desc's
> > > dt_compat is declared as
> > > 
> > > 	const char **dt_compat;
> > > 
> > > .)
> > > 
> > > With the patch below, arch/arm/mach-omap2/board-generic.c compiles just
> > > fine. Don't know yet if the additional const in <asm/mach_desc.h> is
> > > problematic ...
> > 
> > Yes OK thanks. It Would be nice to have those as __initconst to discard
> > the unused ones.
> __initdata is discarded, too, but I already send a patch that adds the
> additional consts. On top of this one the patch from this thread is
> fine.

OK great thanks. I'll apply both into omap-for-v3.18/fixes-not-urgent.

Regards,

Tony
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