Re: [linux-fbdev] [PATCH 2.3.x] fbdev reversion

Hi all,

On  14 Mar, this message from Geert Uytterhoeven echoed through cyberspace:

quoted

Well, while we are at it, we could also work on fixing the PCI problems:
Instead of relying on XFree knowing the host bridge and deducing the
iobase, I beleive we should export from the kernel either one iobase per
PCI device (there can be different busses with different iobases, that's
the case on the new macs and they have the same bus number), or we can
have /proc/bus/pci export "fixed'up" IO addresses (already including the
iobase).

I'd clearly vote for this approach. Something along those lines is
neede as well if you want to use more than one IDE controller at the
same time (or anything other than Apple's integrated controller, for
that matter).

quoted

I can code those fixes, but I'm not sure what solution has most chances
of beeing accepted (especially changing /poc/bus/pci semantics). The
problem is that exporting an IO address alone (without the iobase) has
really no meaning on arch that don't have a x86-like separate IO space at
the CPU level.

I have just yesterday completed my patch doing exactly that (ported
over from 2.2.x); it is, however, PowerMac-only. It's attached below,
and also fixes the missing scan of PCI buses other than bus 0 on
PowerMacs.

Have you talked to Martin Mares about this?

Martin, what is your feeling about this? I think the IO-port-fixup
scheme could be generalized on PPC (or any PCI platform lacking true IO
space); however, it would be best if there were a generic way to find
out the processor base address of the IO space of a specific bus. On
PowerMacs, we get that from OF.

I'm thinking about something along the lines of a resource of the
parent bridge's PCI dev; much like it is available for P2P bridges. So
even though the information is not given directly by host bridges, the
platform fixup code would need to provide those through other means
(typically something firmware-derived).

This would be a step in the direction of a complete resource tree
starting at the host bridges, which, at least on PMacs, is not there
right now. That is needed, however, if dynamic resource allocation is
to produce working results ;-)

Please try this patch if you expierence PCI trouble, and also if you
have IDE in your machine; I'd like to verify I didn't break built-in
PowerMac IDE. Be warned, however....

Flames, comments, cookies, ideas? Beer?

Michel

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