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

[Arnd Bergmann]

On Tuesday 11 December 2012, Russell King - ARM Linux wrote:
> 
> On Tue, Dec 11, 2012 at 04:15:02PM +0000, Arnd Bergmann wrote:
> > On Tuesday 11 December 2012, Thomas Petazzoni wrote:
> > > On Tue, 11 Dec 2012 10:43:49 +0000, Arnd Bergmann wrote:
> > > > On Friday 07 December 2012, Thomas Petazzoni wrote:
> > > > > The pcim_*() functions are used by the libata-sff subsystem, and this
> > > > > subsystem is used for many SATA drivers on ARM platforms that do not
> > > > > necessarily have I/O ports.
> > > > 
> > > > I think this one is wrong as the CONFIG_HAS_IOPORT does not refer to the
> > > > presence of PIO ports but to whether or not they provide an ioport_map
> > > > function. If there is no ioport_map(), devm_pci_iomap will fail to link
> > > > as far as I can tell.
> > > 
> > > The problem is that on ARCH_MULTI_V7, ARCH_VEXPRESS is forcefully
> > > enabled. And ARCH_VEXPRESS selects NO_IOPORT.. so you don't have the
> > > pcim_*() functions, and therefore libata-sff.c (needed for many SATA
> > > drivers) will not build. How do you solve this?
> > 
> > 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.
> 
> No.  ARCH_VEXPRESS selects NO_IOPORT because it does not support
> PCI/ISA IO space.  That in itself is reasonable, but what isn't
> reasonable is the negative logic being used.  Negative logic in
> the config system always tends to provoke this kind of sillyness
> because you're selecting something to be excluded which another
> platform may require.

Exactly, that is what I meant. Sorry if I wasn't clear enough.

> We should instead have HAVE_IOPORT and platforms which need ISA/PCI IO
> space support should select this symbol instead - so it becomes an
> inclusive feature rather than an exclusive feature.

Right. Note that HAS_IOPORT already exists and is defined as

config HAS_IOPORT
        boolean
        depends on HAS_IOMEM && !NO_IOPORT
        default y

If we change it to

config HAS_IOPORT
        boolean
        depends on HAS_IOMEM
        default !NO_IOPORT

then we can actually select both NO_IOPORT and HAS_IOPORT with the result
of getting HAS_IOPORT. It is a bit confusing though to have both enabled,
so we might still want to use an approach where we only select NO_IOPORT
if we are sure that we can't have it.

	Arnd
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