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    SubjectRe: [PATCH] drivers: Let several drivers depends on HAS_IOMEM for 'devm_ioremap_resource'
    On 07/20/2014 04:38 PM, Chen Gang wrote:
    > On 07/19/2014 02:02 AM, Chen Gang wrote:
    >>> 2014-07-18 18:51 GMT+08:00 Richard Weinberger <richard@nod.at>:
    >>>> Am 18.07.2014 12:44, schrieb Chen Gang:
    >>>>> On 07/18/2014 03:35 PM, Richard Weinberger wrote:
    >>>>>> Am 18.07.2014 02:36, schrieb Chen Gang:
    >>>>>>>
    >>>>>>> On 07/18/2014 02:09 AM, Richard Weinberger wrote:
    >>>>>>>> Am 17.07.2014 12:48, schrieb Arnd Bergmann:
    >>>>>>>>> AFAICT, NO_IOMEM only has a real purpose on UML these days. Could we take
    >>>>>>>>> a shortcut here and make COMPILE_TEST depend on !UML? Getting random stuff
    >>>>>>>>> to build on UML seems pointless to me and we special-case it in a number of
    >>>>>>>>> places already.
    >>>>>>>>
    >>>>>>>> If UML is the only arch without io memory the dependency on !UML seems
    >>>>>>>> reasonable to me. :-)
    >>>>>>>>
    >>>>>>>
    >>>>>>> For me, if only uml left, I suggest to implement dummy functions within
    >>>>>>> uml instead of let CONFIG_UML appear in generic include directory. And
    >>>>>>> then remove all HAS_IOMEM and NO_IOMEM from kernel.
    >>>>>>
    >>>>>> Erm, this is something completely different.
    >>>>>> I thought we're focusing on COMPILE_TEST?
    >>>>>>
    >>>>>
    >>>>> COMPILE_TEST is none-architecture specific, but UML is. So in generic
    >>>>> include folder, if we're focusing on choosing whether COMPILE_TEST or
    >>>>> UML, for me, I will choose COMPILE_TEST.
    >>>>>
    >>>>> If we're not only focusing on COMPILE_TEST, for me, if something only
    >>>>> depend on one architecture, I'd like to put them under "arch/*/" folder.
    >>>>>
    >>>>> Especially, after that, we can remove all HAS_IOMEM and NO_IOMEM, nobody
    >>>>> has to think of them again. :-)
    >>>>
    >>>> And then we end up with a solution that on UML a lot of completely useless
    >>>> drivers are build which fail in various interesting manners because you'll
    >>>> add stubs for all kinds of io memory related functions to arch/um/?
    >>>> We had this kind of discussion already. You'll need more than ioremap...
    >>>>
    >>>> I like Arnd's idea *much* more to make COMPILE_TEST depend on !UML.
    >>>>
    >>
    >> That will let UML itself against COMPILE_TEST (but all the other
    >> architectures not).
    >>
    >> And if let COMPILE_TEST depend on !UML, can we still remove all
    >> HAS_IOMEM and NO_IOMEM from kernel? (I guess so).
    >>
    >> If we can remove them, we can send related patch firstly -- that will
    >> let current discussion be in UML architecture wide instead of kernel
    >> wide.
    >>
    >
    > Next, I shall:
    >
    > - Remove HAS_IOMEM and NO_IOMEM from kernel, firstly.
    >
    > - Try to make dummy IOMEM functions for score architecture.
    >
    > - Continue discussing with UML for it.
    >

    Oh, sorry, I forgot, after remove IOMEM from kernel, also s390 and tile
    need implement dummy IOMEM if !PCI.

    If possible, I shall try to implement the dummy IOMEM in 'asm-generic',
    and let uml, score, s390 and tile use them when they need.

    >
    > By the way: how about HAS_DMA? can we treat it as HAS_IOMEM (remove
    > it from kernel)? (for me, I guess we can not).
    >
    >
    > At present, I shall finish sending patch for removing IOMEM today, and
    > continue to welcome any ideas, suggestions or completions for IOMEM or
    > DMA.
    >
    >

    Thanks.
    --
    Chen Gang

    Open share and attitude like air water and life which God blessed


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