diff options
| author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2020-12-11 21:17:35 +0100 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2020-12-11 17:20:36 -0600 |
| commit | aa0b1574fd36f6929f0a3094342a08622c80b4d1 (patch) | |
| tree | 61f2e19c30b5b7118badd46097cbd652374bbe99 | |
| parent | 0af6e21eed2778e68139941389460e2a00d6ef8e (diff) | |
PCI/ACPI: Fix companion lookup for device 0 on the root bus
In some cases acpi_pci_find_companion() returns an incorrect device object
as the ACPI companion for device 0 on the root bus (bus 0).
On the affected systems that device is the PCI interface to the host bridge
and the "ACPI companion" returned for it corresponds to a non-PCI device
located in the SoC (e.g. a sensor on an I2C bus). As a result of this, the
ACPI device object "attached" to PCI device 00:00.0 cannot be used for
enumerating the device that is really represented by it which (of course)
is problematic.
Address that issue by preventing acpi_pci_find_companion() from returning a
device object with a valid _HID (which by the spec should not be present
uder ACPI device objects corresponding to PCI devices) for PCI device
00:00.0.
[bhelgaas: use pci_is_root_bus()]
Link: https://lore.kernel.org/linux-acpi/1409ba0c-1580-dc09-e6fe-a0c9bcda6462@gmail.com/
Link: https://lore.kernel.org/r/4673285.9aE2nYKHPr@kreacher
Reported-by: Daniel Scally <djrscally@gmail.com>
Tested-by: Daniel Scally <djrscally@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Daniel Scally <djrscally@gmail.com>
| -rw-r--r-- | drivers/pci/pci-acpi.c | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c index bf03648c2072..4937de8250ca 100644 --- a/drivers/pci/pci-acpi.c +++ b/drivers/pci/pci-acpi.c @@ -1162,14 +1162,34 @@ void acpi_pci_remove_bus(struct pci_bus *bus) static struct acpi_device *acpi_pci_find_companion(struct device *dev) { struct pci_dev *pci_dev = to_pci_dev(dev); + struct acpi_device *adev; bool check_children; u64 addr; check_children = pci_is_bridge(pci_dev); /* Please ref to ACPI spec for the syntax of _ADR */ addr = (PCI_SLOT(pci_dev->devfn) << 16) | PCI_FUNC(pci_dev->devfn); - return acpi_find_child_device(ACPI_COMPANION(dev->parent), addr, + adev = acpi_find_child_device(ACPI_COMPANION(dev->parent), addr, check_children); + + /* + * There may be ACPI device objects in the ACPI namespace that are + * children of the device object representing the host bridge, but don't + * represent PCI devices. Both _HID and _ADR may be present for them, + * even though that is against the specification (for example, see + * Section 6.1 of ACPI 6.3), but in many cases the _ADR returns 0 which + * appears to indicate that they should not be taken into consideration + * as potential companions of PCI devices on the root bus. + * + * To catch this special case, disregard the returned device object if + * it has a valid _HID, addr is 0 and the PCI device at hand is on the + * root bus. + */ + if (adev && adev->pnp.type.platform_id && !addr && + pci_is_root_bus(pci_dev->bus)) + return NULL; + + return adev; } /** |