Re: [PATCH v12 10/12] PCI: Assign unassigned bus resources in pci_scan_root_bus()

[Suravee Suthikulpanit]

On 09/23/2014 08:41 PM, Bjorn Helgaas wrote:
> On Tue, Sep 23, 2014 at 7:18 PM, Liviu Dudau <liviu@xxxxxxxxxxx> wrote:
> > On Tue, Sep 23, 2014 at 08:01:12PM +0100, Liviu Dudau wrote:
> > > If the firmware has not assigned all the bus resources and
> > > we are not just probing the PCIe busses, it makes sense to
> > > assign the unassigned resources in pci_scan_root_bus().
> > >
> > > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> > > Cc: Arnd Bergmann <arnd@xxxxxxxx>
> > > Cc: Jason Gunthorpe <jgunthorpe@xxxxxxxxxxxxxxxxxxxx>
> > > Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> > > Signed-off-by: Liviu Dudau <Liviu.Dudau@xxxxxxx>
> > > ---
> > >   drivers/pci/probe.c | 3 +++
> > >   1 file changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> > > index ef891d2..508cf61 100644
> > > --- a/drivers/pci/probe.c
> > > +++ b/drivers/pci/probe.c
> > > @@ -1953,6 +1953,9 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
> > >        if (!found)
> > >                pci_bus_update_busn_res_end(b, max);
> > >
> > > +     if (!pci_has_flag(PCI_PROBE_ONLY))
> > > +             pci_assign_unassigned_bus_resources(b);
> > > +
> > >        pci_bus_add_devices(b);
> > >        return b;
> > >   }
> > > --
> > > 2.1.0
> >
> > Bjorn,
> >
> > If you are OK with this patch, can you let me know how do you feel about
> > making pci_scan_root_bus() set up the bus->msi pointer as well?
>
> I'm not opposed to it, but I have the same question as for setting up
> the domain: how does pci_scan_root_bus() learn what to assign to
> bus->msi?  It currently only gets a "void *sysdata" so there's no
> obvious place to put it there.  You could add a pcibios interface to
> retrieve it, I suppose, but I'm starting to get uncomfortable with
> adding more of those because we have such a mess of them already.
>
> Bjorn

[Suravee] Liviu and I had a talk during Linaro Connect, and we came up
with a new binding for the pcie controller called "msi-parent" which is
supposed to contain phandle to the corresponded msi-controller.

> > Side note: I don't know exactly how to do it now, but setting bus->msi is
> > needed by platforms that are based on my patches and want to use MSI,
> > otherwise they have to open code pci_scan_root_bus() to set it. I haven't
> > made any attempts to do it in this series as the GICv2m patches are not
> > ready yet, but I can see the need arriving soon.

[Suravee] I just sent out an RFC which implements the described binding 
here.

https://lkml.org/lkml/2014/9/28/149

Any feedback/comments are welcome :)

Thanks,

Suravee
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