Re: [PATCH 2/2] s390/pci: handle function enumeration after sriov enablement

On Fri, 14 Dec 2018, Christoph Hellwig wrote:

On Fri, Dec 14, 2018 at 05:12:45AM -0800, Christoph Hellwig wrote:

quoted

On Thu, Dec 13, 2018 at 06:54:28PM +0100, Sebastian Ott wrote:

quoted

Implement pcibios_sriov_{add|del}_vfs as empty functions. VF
creation will be triggered by the hotplug code.

And instead of having the arch suplply a no-op arch override I
think it would be better to have the config option just stub it
out in common code.

Or in fact maybe even a runtime flag in struct pci_dev.  Who knows
if all future s390 PCIe busses will have exactly the same behavior
or if we eventually get the standards compliant behvior back?

Something like this:
https://lore.kernel.org/linux-pci/20181212215453.GJ99796@google.com/T/#m649d86ea3c65f669c74d048f89afbaf473876ac3 (local)

Not a runtime flag, but a function pointer in struct pci_host_bridge.
This would provide the requested flexibility. The problem with this
approach is that it requires other patches that are not yet upstream
(https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git/log/?h=pci-probe-rework).

Since this discussion is going on since a few months and I want to
have this code upstream and in distributions for HW enablement I've
asked Bjorn to go with the initial approach (weak functions) and
promised to move that to struct pci_host_bridge once Arnd's patches
are upstream. Would that be OK for you too?

Regards,
Sebastian