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    SubjectRe: [PATCH] spi: Force the registration of the spidev devices
    Hi Greg,

    On Wed, May 13, 2015 at 08:37:40AM -0700, Greg Kroah-Hartman wrote:
    > On Wed, May 13, 2015 at 12:26:04PM +0100, Mark Brown wrote:
    > > On Tue, May 12, 2015 at 10:33:24PM +0200, Maxime Ripard wrote:
    > >
    > > > While this is nicer than the DT solution because of its accurate hardware
    > > > representation, it's still not perfect because you might not have access to the
    > > > DT, or you might be driving a completely generic device (such as a
    > > > microcontroller) that might be used for something else in a different
    > > > context/board.
    > >
    > > Greg, you're copied on this because this seems to be a generic problem
    > > that should perhaps be solved at a driver model level - having a way to
    > > bind userspace access to devices that we don't otherwise have a driver
    > > for. The subsystem could specify the UIO driver to use when no other
    > > driver is available.
    >
    > That doesn't really work. I've been talking to the ACPI people about
    > this, and the problem is "don't otherwise have a driver for" is an
    > impossible thing to prove, as you never know when a driver is going to
    > be loaded from userspace.
    >
    > You can easily bind drivers to devices today from userspace, why not
    > just use the built-in functionality you have today if you "know" that
    > there is no driver for this hardware.

    What we're really after here is that we want to have an spidev
    instance when we don't even have a device.

    And since SPI isn't really doing any kind of hotplug, the only
    situation that might be problematic is if we have the DT overlays
    registering new devices.

    Maxime

    --
    Maxime Ripard, Free Electrons
    Embedded Linux, Kernel and Android engineering
    http://free-electrons.com
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