Re: [PATCH V5 3/3] powerpc/fsl-pci: Unify pci/pcie initialization code

On 08/08/2012 10:48 PM, Jia Hongtao-B38951 wrote:

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-----Original Message-----
From: Wood Scott-B07421
Sent: Wednesday, August 08, 2012 11:58 PM
To: Jia Hongtao-B38951
Cc: Wood Scott-B07421; Li Yang-R58472; linuxppc-dev@lists.ozlabs.org;
Gala Kumar-B11780
Subject: Re: [PATCH V5 3/3] powerpc/fsl-pci: Unify pci/pcie
initialization code

On 08/08/2012 04:03 AM, Jia Hongtao-B38951 wrote:

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-----Original Message-----
From: Wood Scott-B07421
Sent: Tuesday, August 07, 2012 11:25 PM
To: Li Yang-R58472
Cc: Wood Scott-B07421; linuxppc-dev@lists.ozlabs.org; Li Yang-R58472;
Jia
Hongtao-B38951
Subject: Re: [PATCH V5 3/3] powerpc/fsl-pci: Unify pci/pcie
initialization code

On 08/06/2012 11:20 PM, Li Yang wrote:

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On Mon, Aug 6, 2012 at 11:09 PM, Scott Wood
[off-list ref]

wrote:

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On 08/05/2012 10:07 PM, Jia Hongtao-B38951 wrote:

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-----Original Message-----
From: Wood Scott-B07421
Sent: Saturday, August 04, 2012 12:28 AM
To: Jia Hongtao-B38951
Cc: linuxppc-dev@lists.ozlabs.org; galak@kernel.crashing.org; Li
Yang- R58472; Wood Scott-B07421
Subject: Re: [PATCH V5 3/3] powerpc/fsl-pci: Unify pci/pcie
initialization code

As I explained before, this has to be done globally, not from the
probe function, so we can assign a default primary bus if there

isn't any ISA.

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 There are bugs in the Linux PPC PCI code relating to not having
any primary bus.

-Scott

In my way of searching ISA you can also assign a default primary
bus in board specific files.

That was meant for when the board file had an alternate way of
searching for the primary bus (e.g. look for i8259), not as a
replacement for the mechanism that guarantees there's a primary bus.

You are causing a regression in the qemu_e500.c platform.

Can we fix the qemu device tree to address the problem if we do make
it a rule to use the ISA node to indicate the primary bus?

No.  There is no ISA, and we're not going to lie and say there is.

But we can assign a default primary for qemu.

Not in the device tree.  What other mechanism do you propose?  And why do
you want to fix it only for QEMU and not other boards, where things
happen to work but not as designed?

Kumar, can you speak up here as maintainer so we can stop going back and
forth endlessly?

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I really don't understand what the problem is with leaving the
primary detection code as global.  Either fix the bugs so we don't
need a primary, or accept some "impurity" in the workaround.

-Scott

Global detection for primary is ok but we think our way is deeper

unified.

So my way works and "is ok", and your way doesn't work but is
theoretically cleaner.

Sorry, I meant global detection is ok but I didn't mean that your logic
is ok. The concern is in some cases there is no isa node in device tree
and the primary is not the first bus. Your logic assigned a wrong primary
there. Is that a problem? Take ge_imp3a as an example.

So maybe we should fix this exceptional board.

Boards like that are why the code first checks for whether
fsl_pci_primary is NULL.  Board code can set fsl_pci_primary based on
other criteria before calling fsl_pci_init().

This is why we need to allow for a gradual conversion, so boards like
that can get personal attention by someone who can test the change.

-Scott