Re: [PATCH 1/3] powerpc/mpc85xx: remove the unneeded pci init functions for corenet ds board

[Kevin Hao <haokexin@gmail.com>]

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On Thu, May 30, 2013 at 01:54:59PM -0500, Scott Wood wrote:
> On 05/30/2013 05:20:34 AM, Kevin Hao wrote:
> >On Tue, May 28, 2013 at 05:52:09PM -0500, Scott Wood wrote:
> >> On 05/21/2013 07:04:58 AM, Kevin Hao wrote:
> >> >It also seems that we don't support ISA on all the current
> >corenet ds
> >> >boards. So picking a primary bus seems useless, remove that
> >function
> >> >too.
> >>
> >> IIRC that was due to some bugs in the PPC PCI code in the absence of
> >> any primary bus.
> >
> >Do you know more about these bugs?
> 
> Not off the top of my head -- either search the archives or ask Ben.
> 
> >>  fsl_pci_assign_primary() will arbitrarily pick one
> >> to be primary if there's no ISA.  Have the bugs been fixed?
> >
> >I know there should be some reason that we put the
> >fsl_pci_assign_primary()
> >here. But frankly I am not sure what bugs this workaround try to
> >fix. For these
> >corenet boards picking one to be primary has no effect to the
> >64bit kernel.
> >And for 32bit kernel, the only effect of this is that isa_io_base
> >is set to the
> >io virtual base of the primary bus. But the isa_io_base only make
> >sense when
> >we do have a isa bus, so that we can access some well-known io
> >ports directly
> >by using outx/inx. But if we don't have isa bus on the board, the
> >value of
> >isa_io_base should make no sense at all. So we really don't need
> >to pick a
> >fake primary bus. Of course I may miss something, correct me if I
> >am wrong. :-)
> 
> outx/inx can also be used for PCI I/O BARs.

Yes, I know there is also PIO. But the value of isa_io_base doesn't
have any effect for this.

Thanks,
Kevin

> 
> -Scott

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