Re: xilinx-pci driver and pci in general

[Michal Simek]

Benjamin Herrenschmidt wrote:
> On Wed, 2010-01-13 at 16:23 +0100, Michal Simek wrote:
>
> > The main problems are:
> > ppc use ppc_md struct which we don't have it on Microblaze.
> > xilinx-pci driver uses exclude_device function. This function is used in 
> > indirect_pci.c too. There could be a way to move that function directly 
> > to pci_controller structure which could be useful for other controllers 
> > too. What do you think?
> >
> > Then there are some other ppc_md. calling like pcibios_after_init which
> > if I see correctly not used for ppc too.
>
> We may not be using after_init() anymore in which case you are welcome
> to send a patch to remove it :-)

hmm. I used older kernel and I see that in the latest version powermac
use it. :-( I will just remove it.

> As for the others, well ... maybe you can do wrappers for these that
> call into ppc_md. on powerpc and into some kind of arch_pci_ops. that
> the platform provides on microblaze ?
>
> I'm not sure moving them into the pci_controller is the best way to go
> there.

ok. I will remove that part of code for now.

> > The next thing is that some files contains asm/machdep.h which could be 
> > added to asm/pci-bridge.h and the same is for asm/ppc-pci.h
>
> Yeah, moving includes like that is ok.
>
> > Files contains CONFIG_PPC_OF and we would like to use only CONFIG_OF.
> > I remember any discuss around but not sure what was the conclusion on 
> > powerpc.
>
> I think that should be allright, Grant, any objection there ?
>
> > Part of headers are the same that's why there will be a space to move 
> > them to asm-generic.
>
> If you can convince other archs that it makes sense to do so ? :-)

will try.

> > Anyway: I look at your dma-mapping.h and you can use 
> > asm-generic/dma-mapping-common.h as I am using.
>
> Not just quite yet, there's still some stuff we need to cleanup with
> the !coherent cases.
>
> > Then I have some question about EARLY_PCI_OP in ppc_32.c. Is there any 
> > reason to use early_##rw##_config_##size fucntions instead of proper 
> > pci_bus_##rw##_config_##size functions?
> > There is one comment that these functions are used before PCI scanning 
> > is done but there are used the same function as are in driver/pci/access.c.
> > Is there any "secret" reason to do it in this way?
>
> Well, first of all, those aren't ppc32 only anymore, they are in
> pci-common.c now. Then, if you look at them you'll notice that
> they are just a wrapper on top of pci_bus_* which uses a fake
> pci_bus structure. IE. They are meant to be used in very early
> arch fixup code at a time when we may not even have the struct
> pci_bus at hand. Their use is pretty rare though, maybe we -could-
> get rid of them at some stage by moving some of that fixup code.

Thanks for that.

> > Thanks for this early discuss. I would like to hear your opinion and 
> > then I will choose solution how to add our pci support to mainline.

I will keep you informed but I see that I will add that part of code to 
mainline and then we look at consolidation work.

Thanks,
Michal

> Cheers,
> Ben.
>
>
>
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--
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian

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