Re: [PATCH v8 30/45] powerpc/pci: Delay populating pdn

On 04/20/2016 12:13 PM, Gavin Shan wrote:

On Tue, Apr 19, 2016 at 06:19:20PM +1000, Alexey Kardashevskiy wrote:

quoted

On 02/17/2016 02:44 PM, Gavin Shan wrote:

quoted

The pdn (struct pci_dn) instances are allocated from memblock or
bootmem when creating PCI controller (hoses) in setup_arch(). PCI
hotplug, which will be supported by proceeding patches, releases
PCI device nodes and their corresponding pdn on unplugging event.
The memory chunks for pdn instances allocated from memblock or
bootmem are hard to reused after being released.

This delays creating pdn by pci_devs_phb_init() from setup_arch()
to core_initcall() so that they are allocated from slab. The memory
consumed by pdn can be released to system without problem during
PCI unplugging time. It indicates that pci_dn is unavailable in
setup_arch() and the the fixup on pdn (like AGP's) can't be carried
out that time. We have to do that in ppc_md.pcibios_root_bridge_prepare()
on maple/pasemi/powermac platforms where/when the pdn is available.

At the mean while, the EEH device is created when pdn is populated,
meaning pdn and EEH device have same life cycle. In turn, we needn't
call eeh_dev_init() to create EEH device explicitly.

Signed-off-by: Gavin Shan <redacted>

Uff. It would not hurt to mention that  pcibios_root_bridge_prepare is called
from subsys_initcall() which is executed after core_initcall() so the code
flow does not change.

Yes, will do in next revision.

quoted

Have you checked if there is anything in between
core_initcall(pci_devs_phb_init) and subsys_initcall(pcibios_init) which
might need device tree nodes? For example, subsys_initcall(pcibios_init)
calls (eventually) pnv_pci_ioda_fixup(), if we are unlucky and pcibios_init()
(and therefore pnv_pci_ioda_fixup() or what pseries/others do) is called
before pcibios_init() - won't we crash or something?

I don't catch what you were asking. device-tree nodes (struct device_node)
are always there. This patch doesn't affect them. Perhaps you were talking
about pdn (PCI_DN). If it's the case, this patch delays creating pdn from
setup_arch() to core_initcall(pci_devs_phb_init).

While thinking of explaining what I wanted to ask, I found my answer :)

pcibios_init() calls ppc_md.pcibios_root_bridge_prepare() first, then 
ppc_md.pcibios_fixup() so we are fine here with ordering.

I don't see anything need pdn between setup_arch() and core_initcall().
The changes introduced to powermac/pasemi platforms are: move fixing the child
pdns of the specifiec PHB's pdn from setup_arch() to subsys_initcall(pcibios_init).
I don't see anything between them needs the fixed pdns.

I don't understand how pcibios_init() is called before pcibios_init() in your

pcibios_init() is used twice in the sentence above :)

Anyway,


Reviewed-by: Alexey Kardashevskiy <redacted>

context. Sorry for my bad English. Perhaps you're asking the the called sequence
on core_initcall() and subsys_init()? If so, they're defined like below:

#define core_initcall(fn)		__define_initcall(fn, 1)
#define subsys_initcall(fn)		__define_initcall(fn, 4)

 >

quoted

--
Alexey

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-- 
Alexey