On Fri, Sep 12, 2014 at 11:13:51AM +0100, Suravee Suthikulpanit wrote:

On 9/8/2014 8:54 AM, Liviu Dudau wrote:

quoted

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@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jason Gunthorpe <redacted>
Cc: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
---
  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;
  }

Liviu,

Besides the check for PCI_PROBE_ONLY here, I think we also need to avoid calling
"pci_enable_resources()" in the "driver/pci/pci.c: pcibios_enable_device()" for
PCI_PROBE_ONLY mode since the resource is not assigned by Linux. Otherwise, the
"drivers/pci/setup-res.c: pci_enable_resource()" would fail w/ error:

     can't enable device: BAR ..... not assigned

Hmm, are you sure that is not because the host bridge resources have not been
requested? pci-host-generic.c uses PCI_PROBE_ONLY and yet it works with the series as
is. But it does request_resource() for the host bridge resources inside the driver.

Best regards,
Liviu

Actually, in "arch/arm/kernel/bios32.c:", the weak "pcibios_enable_device()" function
also has the check for PCI_PROBE_ONLY mode before calling pci_enable_resources().

Thanks,

Suravee

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