Re: [PATCH] generic check_legacy_ioport

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Wed, 2007-04-25 at 00:01 +0200, Arnd Bergmann wrote:
> On Tuesday 24 April 2007, Olaf Hering wrote:
> > 
> > > Do you think a device_type fdc, i8042 or ipmi will appear outside an isa
> > > node?
> > 
> > Does anyone know where those ipmi devices appear in the device-tree?
> 
> There are actually _no_ ipmi devices that we expect to appear here.
> the reason why the check is in the ipmi driver is in order not to crash
> on powerpc machines that load the ipmi driver but have no ipmi nodes
> in the device tree.

To be totally correct, there might well be, but we shouldn't care.

That is, if a device XXX (let's say XXX is ipmi but it could be i8042 or
whatever else) exist in the device-tree outside of the ISA bus, then it
needs it's own platform or of_platform device to be probed and shouldn't
make the check_legacy_io_port() go true.

There are various cases (especially in embedded world) where "standard"
components have been puts in ASICs but at funky/different addresses, and
they shouldn't be hit by the legacy probe.

Thus, the default implementation of check_legacy_ioport() should only
match things that are under an "isa" bus. Anything else needs to be
handled either by a platform specific check_legacy_ioport() override via
ppc_md (if it's really some legacy stuff and under a fucked up
device-tree) or via driver specific alternate probing method (like an
of_platform_device).

Ben.