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    SubjectRe: [PATCH 0/5] mfd: replace IORESOURCE_IO by IORESOURCE_MEM
    On Tue, Aug 07, 2012 at 09:47:25AM +0800, Haojian Zhuang wrote:
    > On Tue, Aug 7, 2012 at 6:00 AM, Mark Brown
    > <broonie@opensource.wolfsonmicro.com> wrote:
    > > On Mon, Aug 06, 2012 at 10:31:24PM +0100, Russell King wrote:
    > >
    > >> Anyway, given that this thread is broken, there's no way for me to find
    > >> out what the _original_ issue is that you're talking about. So I'm going
    > >> to guess that it's come up because we're out of IORESOURCE bits.
    > >
    > > No, that's not it. What's happened is that Haojian has posted some
    > > patching changing all the _IO resources to _MEM in the Marvell PMIC
    > > drivers, I think because you yelled at him for using _IO when he
    > > reported that the changes in ioport_resource broke things a few releases
    > > ago. Obviously this doesn't achieve a huge amount, it's a misplaced
    > > cleanup.
    > >
    > It's because IO_SPACE_LIMIT is set as 0 if there's no PCI devices. But
    > IORESOURCE_IO is also used in PMIC mfd drivers to distinguish
    > different components.
    >
    > commit 04e1c83806e30ae339fc45def595960c7fef1697
    > Author: Russell King <rmk+kernel@arm.linux.org.uk>
    > Date: Wed Jul 6 12:49:59 2011 +0100
    >
    > ARM: io: add a default IO_SPACE_LIMIT definition
    >
    > Add a default IO_SPACE_LIMIT definition. Explain the chosen value and
    > suggest why platforms would want to make it larger.
    >
    > Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
    >
    > >> So, if we made this a numeric index, then we have 32 resource types
    > >> to deal with, and no need to bugger around with re-using an existing
    > >> type for something else.
    > >
    > > This seems sensible, and I'm sure if that change were made people would
    > > be delighed to use new resource types, but like I say nobody who's
    > > motivated to do anything here seems to have the time to do anything
    > > about it.
    > >
    > > Whoever looks at this would need to do some detective work, it does seem
    > > like there must have been a reason to use a bitmask here...
    >
    > Changing bitmask to a value for IORESOURCE type is a risk. I agree on Mark
    > that someone will complain on this.

    We won't know that unless we try and propose to do it in patch form.
    From what I can see, there is nothing in the kernel which technically
    prevents us from doing this.

    > Could we consider to expand the usage of IORESOURCE_IO? Maybe we can
    > use it for both ISA/PCI and IO related in chip.

    If it's not clear, I am *completely* against this. It's a hack and bodge,
    and therefore doesn't belong in the kernel.

    --
    Russell King
    Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
    maintainer of:


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