Re: [RFC/RFT PATCH v2 3/3] PCI/ACPI: Add ACPI pci_bus_find_numa_node() implementation

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Tue, May 16, 2017 at 05:15:29PM +0200, Robert Richter wrote:
> On 15.05.17 14:22:05, Lorenzo Pieralisi wrote:
> > The introduction of pci_bus_find_numa_node(pci_bus) allows at PCI
> > host bridge registration to detect the NUMA node for a given
> > struct pci_bus.dev. Implement an ACPI method that, through
> > the struct pci_bus.bridge ACPI companion, retrieve and return
> > the NUMA node corresponding to a given struct pci_bus.dev.
> > 
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> > Cc: Bjorn Helgaas <bhelgaas@google.com>
> > ---
> >  drivers/pci/pci-acpi.c | 20 ++++++++++++++++++++
> >  drivers/pci/pci.c      |  2 +-
> >  include/linux/pci.h    |  6 ++++++
> >  3 files changed, 27 insertions(+), 1 deletion(-)
> > 
> 
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index e9803c1..451342d 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -5406,7 +5406,7 @@ int pci_bus_find_domain_nr(struct pci_bus *bus, struct device *parent)
> >  
> >  int pci_bus_find_numa_node(struct pci_bus *bus)
> >  {
> > -	return NUMA_NO_NODE;
> > +	return acpi_disabled ? NUMA_NO_NODE : acpi_pci_bus_find_numa_node(bus);
> 
> I looked into how this works with devicetree.
> 
> With ACPI it is set directly in pci_register_host_bridge() with
> set_dev_node().
> 
> For the DT case the set_dev_node call sets it to NUMA_NO_NODE first.
> Since in DT the bridge is a platform device which has the node id
> assigned already (if there is one), the bus' node id is set later in
> device_add() when deriving it from the parent device which is the
> bridge. So this should work.

Which also means that the node propagation for bus->dev in patch 2 can
be probably removed :), the problem with ACPI is setting the node
for the host bridge which in DT is done by default at platform device
creation, the rest is done by the core already there is not any need
to propagate it again when child busses are created (they take their
node from the parent).

Thanks for the heads-up and testing,
Lorenzo

> I have tested it both DT and ACPI.
> 
> Thanks,
> 
> -Robert
> 
> >  }
> >  
> >  /**