Messages in this thread | | | From | Bjorn Helgaas <> | Date | Mon, 29 Sep 2014 12:17:29 -0600 | Subject | Re: [RFC 3/4] arm64: Do not call enable PCI resources when specify PCI_PROBE_ONLY |
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On Sun, Sep 28, 2014 at 2:53 PM, <suravee.suthikulpanit@amd.com> wrote: > From: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> > > When specify PCI_PROBE_ONLY, the resource parent does not get assigned. > Therefore, pci_enable_resources() return error saying that > "BAR x not claimed". > > Note: This same logic is also used in the arch/arm/kernel/bios32.c > > Cc: Liviu Dudau <Liviu.Dudau@arm.com> > Cc: Bjorn Helgaas <bhelgaas@google.com> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> > --- > arch/arm64/kernel/pci.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c > index ce5836c..7fd4d2b 100644 > --- a/arch/arm64/kernel/pci.c > +++ b/arch/arm64/kernel/pci.c > @@ -68,3 +68,11 @@ void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent) > bus->domain_nr = domain; > } > #endif > + > +int pcibios_enable_device(struct pci_dev *dev, int mask) > +{ > + if (pci_has_flag(PCI_PROBE_ONLY)) > + return 0; > + > + return pci_enable_resources(dev, mask);
I had thought of "PCI_PROBE_ONLY" as the "look but don't touch" flag, i.e., never change any BAR or bridge window assignments. But I guess the current usage is more general than that: we also use it to
- avoid pci_enable_resources(), which only turns on IO/MEM bits in the command register - avoid pcie_bus_configure_settings(), which programs MPS and MRRS - avoid pci_read_bridge_bases(), which really just *reads* bridge windows - avoid pcibios_reserve_legacy_regions(), which doesn't touch any PCI registers - enables pci_claim_resource()
This seems like more than necessary, but I don't know all the history. In particular, I don't know why PCI_PROBE_ONLY should make a difference to things like claiming resources.
> +} > -- > 1.9.3 >b
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