Re: pci in arch/powerpc vs arch/ppc

On Tue, 07 Aug 2007 18:20:12 +0300, Scott Wood [off-list ref]=
  =

wrote:

Alexandros Kostopoulos wrote:

quoted

Except from some macros arch/powerpc/include/asm/io.h / mpc8260_pci9.=

h,  =

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I  can seem to find anywhere the code regarding PCI Erratum 9. The  =

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defined  macros(in io.h) for read/write are sufficient as a workaroun=

d  =

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for PCI9?  Who does DMA and register initialization for this (it used=

  =

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to be done in  arch/ppc/syslib/m8260_pci_erratum9.c in arc/ppc). Mayb=

e  =

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u-boot or the  bootwrapper?

I don't think the workaround exists yet in arch/powerpc, despite the  =

config option.

Is there a plan to be implemented on arch/powerpc, or devices with the  =

erratum will have to keep on using the legacy arch/ppc code?

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Another question regarding resource allocation: when   =

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alloc_resource(pci_32.c), called from pcibios_allocate_resources(),  =

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during  pcibios init, attempts to allocate resources using  =

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request_resource(), the  request fails. This seems to happen because =

 =

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the previously scanned PCI  devices request resources in the form, e.=

g.  =

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00000- 0000f (i.e. starting  from zero), and this should be mapped  =

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somewhere else in cpu mem space. My  question (in order to find my bu=

g)  =

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is, who performs this mapping, from PCI  space to CPU space, the kern=

el  =

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(and if yes, where?) or the host bridge (in  which case, I've probabl=

y  =

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failed to configure it properly).

If the error message is the one I'm thinking of (it always helps to po=

st  =

the actual messages), that's normal for when the PCI bus hasn't been  =

probed by the firmware.  Linux first tries to use the BARs as they're =

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already set, which will obviously fail because they haven't been set, =

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and then it will properly allocated them.  It's harmless verbosity,  =

though it'd be nice to have a flag to tell the PCI layer to not bother=

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trying to preserve any existing BARs.

Well, the error message is:
PCI:0000:00:16.0: Resource 0: 0000000000000000-0000000000000fff (f=3D200=
)
PCI: Cannot allocate resource region 0 of device 0000:00:16.0
PCI:  parent is c03c4058: 0000000080000000-00000000bfffffff (f=3D200)

The thing is, POBARs are already setup by uboot. However the resource  =

allocation for the PCI devices (not the host bridge) fails in  =

request_resource (which seems to use the region requested by the device =
as  =

is and not some mapped region in the cpu address space), and I can not  =

find where in the code happens the mapping from PCI to local bus mem  =

region. I mean, each PCI device requests some region, e.g. from 0000-00f=
f  =

and this is mapped to some region in the PCI outbound window, right. For=
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some reason this fails in my case, and I cannot find where in the code  =

this mapping should happen.

Thank you for your help

Alex

-Scott