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    SubjectRe: [PATCH 4/7] gpiolib: implement dev_gpiochip_{add,remove} calls
    On Wed, Oct 22, 2008 at 02:52:46PM -0700, David Brownell wrote:
    > On Wednesday 22 October 2008, Anton Vorontsov wrote:
    > > >
    > > > > So if we register the board infos after
    > > > > the controller registered, then nobody will probe the board infos.
    > > >
    > > > See above.  If you're doing it right, there's no problem.
    > > > That is, scan the OF tables early.  Just like PNP tables
    > > > get scanned early, for example.
    > >
    > > Heh. If we don't want to be able to make the OF-parsing code
    > > be a module then there is no problem at all. I can use the bus
    > > notifiers. And it is most straightforward solution then.
    > >
    > > But I quite dislike to bloat the kernel image with
    > > maybe-never-used-on-this-board code.
    > So have it live in the __init text section. If you're
    > building a kernel with support for several boards, you
    > know it's necessarily going to be larger than it would
    > be if only one board were supported. But you can shrink
    > kernel size by judicious use of __init sections..

    Won't work, unfortunately. I2C devices are created by the
    i2c controllers, via drivers/of_i2c.c of_register_i2c_devices().

    There is a good reason to do so, the code needs to know
    controller's OF node to walk down and register the child nodes
    (devices). See drivers/i2c/busses/i2c-mpc.c -- it calls
    of_register_i2c_devices() at the end of the probe().

    Since we can't call __init stuff from non-__init, the scheme
    you purpose won't work.

    The same is for SPI (drivers/of_spi.c of_register_spi_devices()).

    > > My aim was to make the
    > > OF-parsing part be a module too. Because in the long run we
    > > need the OF-parsing stuff for _every_ driver that needs
    > > platform data. It's quite expensive to have it always built-in,
    > > don't you think?
    > If it's discarded early, after translating the data from
    > OF format into what the drivers need, there will be no
    > RAM footprint.

    There is also kernel image size that matters...

    Anton Vorontsov
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