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.
-Scott
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