linux-kernel - Re: [RFC v1 01/16] lib: devres: don't enclose pcim_*() functions in CONFIG_HAS

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Date:	Tue, 11 Dec 2012 17:30:13 +0100
From:	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Jason Cooper <jason@...edaemon.net>,
	Andrew Lunn <andrew@...n.ch>,
	Gregory Clement <gregory.clement@...e-electrons.com>,
	Lior Amsalem <alior@...vell.com>,
	Yehuda Yitschak <yehuday@...vell.com>,
	Tawfik Bayouk <tawfik@...vell.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...onic-design.de>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	linux-kernel@...r.kernel.org,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	"Eran Ben-Avi" <benavi@...vell.com>,
	Nadav Haklai <nadavh@...vell.com>,
	Maen Suleiman <maen@...vell.com>,
	Shadi Ammouri <shadi@...vell.com>,
	Yinghai Lu <yinghai@...nel.org>
Subject: Re: [RFC v1 01/16] lib: devres: don't enclose pcim_*() functions in
 CONFIG_HAS_IOPORT

Dear Arnd Bergmann,

On Tue, 11 Dec 2012 16:15:02 +0000, Arnd Bergmann wrote:

> What you describe here are probable two bugs, and we should fix both:
> 
> * ARCH_VEXPRESS should not select NO_IOPORT. It's generally wrong
>   to select this in combination with ARCH_MULTIPLATFORM, when some
>   of the other platforms you may enable actually have IOPORT mapping
>   support.

Indeed, but I guess the "select NO_IOPORT" on vexpress is here for a
reason, no?

That said, unless I don't understand what IOPORTs are, I don't think my
platform has any of them, so why should I "select HAVE_IOPORT" ?

> * We should not unconditionally select ARCH_VEXPRESS from ARCH_MULTIPLATFORM.
>   There is no reason why we would enable that platform for building
>   a kernel that runs on only one other platform.

This one is already being worked on by Fabio Estevam, see [PATCH v2]
ARM: Kconfig: Do not force selection of ARCH_VEXPRESS by ARCH_MULTI_V7.

> > I'm not sure which devm_pci_iomap() you're referring to since my patch
> > makes only the pcim_iomap_table(), pcim_iomap(), pcim_iounmap(),
> > pcim_iomap_regions(), pcim_iomap_regions_request_all() and
> > pcim_iounmap_regions() available under CONFIG_PCI instead of CONFIG_PCI
> > && CONFIG_HAS_IOPORT.
> 
> Sorry, I meant pcim_iomap.
> 
> > So maybe you were referring to pcim_iomap(). I haven't checked in
> > details, but I guess it builds because ioport_map() is implemented in
> > arch/arm/mm/iomap.c.
> 
> Right. If an ioport_map function is provided for a given platform,
> we should also set HAVE_IOPORT and vice versa. This is probably
> fallout of the io.h conversion for multiplatform.

arch/arm/mm/iomap.c is unconditionally compiled in all ARM kernels. And
in this file, ioport_map() and ioport_unmap() are implement as soon as
__io is defined. And basically, in arch/arm/include/asm/io.h, __io is
defined for all platforms, except maybe on some platforms having their
own mach/io.h file, but those are quite limited in number (ebsa110, rpc,
at91, s3c24xx, pxa, omap1, footbridge and ixp4xx). So if __io is
defined, says on VEXPRESS, why does it "select NO_IOPORT" ? Essentially
all ARM platforms should select HAVE_IOPORT, except the few ones that
don't define __io. Correct?

Thanks,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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