Re: [PATCH v4 3/5] PCI: Handle IORESOURCE_PCI_FIXED when sizing and assigning resources.

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On 10/02/2015 04:14 PM, Yinghai Lu wrote:
On Fri, Oct 2, 2015 at 3:37 PM, David Daney <ddaney.cavm@xxxxxxxxx> wrote:
From: David Daney <david.daney@xxxxxxxxxx>

The new Enhanced Allocation (EA) capability support creates resources
with the IORESOURCE_PCI_FIXED set.  This creates a couple of problems:

1) Since these resources cannot be relocated or resized, their
    alignment is not really defined, and it is therefore not specified.
    This causes a problem in pbus_size_mem() where resources with
    unspecified alignment are disabled.

2) During resource assignment in pci_bus_assign_resources(),
    IORESOURCE_PCI_FIXED resources are not given a parent.  This, in
    turn, causes pci_enable_resources() to fail with a "not claimed"
    error.

So, in pbus_size_mem() skip IORESOURCE_PCI_FIXED resources, instead of
disabling them.

In __pci_bus_assign_resources(), for IORESOURCE_PCI_FIXED resources,
try to request the resource from a parent bus.

Can you check if

https://patchwork.kernel.org/patch/7304971/
[v6,05/53] PCI: Don't release fixed resource for realloc


This one isn't relevant as the problem is seen when we are acquiring resources, not releasing them.


https://patchwork.kernel.org/patch/7304371/
[v6,06/53] PCI: Claim fixed resource during remove/rescan path

This one is interesting, but I don't think it will work.

pci_claim_resource() calls pci_find_parent_resource(), which will fail in important use cases.

It is perfectly legal for a bridge provisioned by EA to not specify any resources. In this case we must walk up the bus tree until we find something that contains the device resource, and can thus be a parent.

That is a big part of what my patch is doing.

As for the merits of assigning fixed resources from the FINAL fixup, rather than in __pci_bus_assign_resources(), I am unsure.

Thanks,
David Daney



address the the problem that you met?

         Yinghai


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