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    SubjectRe: [sodaville] [PATCH 03/11] x86/dtb: Add a device tree for CE4100
    On Mon, 2010-11-29 at 20:36 +0100, Sebastian Andrzej Siewior wrote:
    > This also works with the flat tree, right?

    Yes, of course. You use similar references in your interrupt-map :-)

    > Okay, so we want this for a quirk at a later point in time. Now I
    > understand.

    More precisely, if something has to depend on a specific
    revision/errata/feature, in the future, it would be problematic to have
    to modify the device-tree.

    The "rule" for compatible is to be a list going from a reasonably
    precise description of the specific device to the more generic
    programming interface the device implements.

    > Would "isa-bridge" be acceptable? So I don't have to add a new bus to
    > the probe list for every new SoC.

    Just call it 'isa', as for device_type, we shouldn't need it.

    The default "probe list" is crap. If you want to have platform devices
    instanciated for the ISA devices from the device-tree, I'd rather you
    explicitely do it from the architecture code. As Scott said, "isa"
    doesn't quite qualify as a "generic" simple bus.

    > Yes. of_address_to_resource() will do the right thing in this case. It
    > can only be used after unflatten_device_tree() and I need this
    > earlier.

    This probably means you are doing the unflattening too late...

    > Now using unflatten_device_tree() earlier isn't that easy, or is it.
    > I defered the ioapic init a little, so it is now called from
    > x86_init.mpparse.get_smp_config() so I have alloc_bootmem() working.

    You can probably do the unflattening way before alloc_bootmem is

    The unflattening does a first pass to scan for the size, so all you need
    is a way to get a single contiguous chunk of memory, I'm sure x86 has
    ways to provide that sort of thing really early before bootmem is
    initialized (what about memblock btw ?).

    > So unflatten_device_tree() seems to work here. The ugly part comes
    > now:
    > early_init_dt_alloc_memory_arch() expects u64 which works with
    > phys_to_virt() and the other way around. This isn't really the case
    > with
    > what __alloc_bootmem(). This looks like phys_map to me. Since the dtb
    > code
    > simply uses phys_to_virt() it doesn't really matter. So it works and
    > I
    > probably can use of_address_to_resource().

    Yeah just __pa what alloc_bootmem returns but as I said, it should
    probably be unflattened earlier than that.

    Peter (CC) should be able to help finding the right spot/API there.


    > > Cheers,
    > > Ben.
    > Sebastian
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