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PCI/ACPI: Fix companion lookup for device 0 on the root bus

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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>
This commit is contained in:
Rafael J. Wysocki 2020-12-11 21:17:35 +01:00 committed by Bjorn Helgaas
parent 0af6e21eed
commit aa0b1574fd
1 changed files with 21 additions and 1 deletions
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22
drivers/pci/pci-acpi.c
View file

@ -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;
}
/**