The current ARM pcibios layer prevents PCI devices resources enablement
if the PCI_PROBE_ONLY global flag is set, since on systems that require
immutable PCI BARs set-up (ie probe only) the arm PCI bios layer does
not assign resources, hence resources are not really checked (ie claimed)
and they do not get assigned a parent, which causes pci_enable_resources
to fail in turn.
If the kernel tries to enable the resources for a PCI device through
pci_enable_resources, it would fail on PCI_PROBE_ONLY systems since the
device resources are not claimed (ie they are not assigned) on those
systems and the resource parent is left uninitialized (ie they have a
dangling parent pointer).
This behaviour does not conform with the expected kernel behaviour.
When a PCI device and its resources are scanned, the detected PCI
resources should be claimed in order to validate their values read
from the BARs set-up and should be assigned a parent resource so that the
resource hierarchy is initialized.
Resource claiming must be carried out on PCI_PROBE_ONLY systems
too, since it is a method for validating resources and it has nothing
to do with PCI_PROBE_ONLY flag.
This patch removes the pcibios_enable_device call from the arm bios32
implementation (which means that arm falls back to the generic weak
version for its implementation, that correctly enables a device resources)
and replaces it with an arm pcibios_add_device implementation, that claims
resources for a device, so that the behaviour becomes compliant with the
expected PCI device kernel initialization flow.
This way, resources are claimed and enabled on PCI_PROBE_ONLY systems
too improving the BAR set-up validation and making the arm kernel PCI
behaviour closer to other architectures.
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
---
arch/arm/kernel/bios32.c | 22 ++++++++++++++++------
1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
index fcbbbb1..aace9ca 100644
--- a/arch/arm/kernel/bios32.c
+++ b/arch/arm/kernel/bios32.c
@@ -604,15 +604,25 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
}
/**
- * pcibios_enable_device - Enable I/O and memory.
- * @dev: PCI device to be enabled
+ * pcibios_add_device - Initialize device before adding it to PCI bus
+ * @dev: PCI device to be added
*/
-int pcibios_enable_device(struct pci_dev *dev, int mask)
+int pcibios_add_device(struct pci_dev *dev)
{
- if (pci_has_flag(PCI_PROBE_ONLY))
- return 0;
+ struct resource *res;
+ int i;
+ /*
+ * Device resources are claimed to validate
+ * them and initialize their hierarchy structure
+ */
+ for (i = 0; i < PCI_NUM_RESOURCES; i++) {
+ res = &dev->resource[i];
+ if (res->parent || !res->flags)
+ continue;
+ pci_claim_resource(dev, i);
+ }
- return pci_enable_resources(dev, mask);
+ return 0;
}
int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
--
2.2.1
--
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