Re: pci in arch/powerpc vs arch/ppc

["Alexandros Kostopoulos" <akostop@inaccessnetworks.com>]

On Tue, 07 Aug 2007 18:20:12 +0300, Scott Wood <scottwood@freescale.com>=
  =

wrote:

> Alexandros Kostopoulos wrote:
>> Except from some macros arch/powerpc/include/asm/io.h / mpc8260_pci9.=
h,  =

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

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

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

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

>> 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?

>> Another question regarding resource allocation: when   =

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

>> during  pcibios init, attempts to allocate resources using  =

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

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

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

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

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

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

>> 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 =
 =

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

> 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=
  =

> 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=
  =

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