diff mbox series

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

Message ID 4673285.9aE2nYKHPr@kreacher (mailing list archive)
State Accepted
Delegated to: Bjorn Helgaas
Headers show
Series PCI: ACPI: Fix up ACPI companion lookup for device 0 on the root bus | expand

Commit Message

Rafael J. Wysocki Dec. 11, 2020, 8:17 p.m. UTC
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

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.

Link: https://lore.kernel.org/linux-acpi/1409ba0c-1580-dc09-e6fe-a0c9bcda6462@gmail.com/
Reported-by: Daniel Scally <djrscally@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/pci/pci-acpi.c |   20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

Comments

Daniel Scally Dec. 11, 2020, 11:02 p.m. UTC | #1
On 11/12/2020 20:17, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> 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.
>
> Link: https://lore.kernel.org/linux-acpi/1409ba0c-1580-dc09-e6fe-a0c9bcda6462@gmail.com/
> Reported-by: Daniel Scally <djrscally@gmail.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Tested and confirmed working on my devices - thanks.


Tested-by: Daniel Scally <djrscally@gmail.com>

Reviewed-by: Daniel Scally <djrscally@gmail.com>


> ---
>  drivers/pci/pci-acpi.c |   20 +++++++++++++++++++-
>  1 file changed, 19 insertions(+), 1 deletion(-)
>
> Index: linux-pm/drivers/pci/pci-acpi.c
> ===================================================================
> --- linux-pm.orig/drivers/pci/pci-acpi.c
> +++ linux-pm/drivers/pci/pci-acpi.c
> @@ -1162,14 +1162,32 @@ void acpi_pci_remove_bus(struct pci_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_dev->bus->parent)
> +		return NULL;
> +
> +	return adev;
>  }
>  
>  /**
>
>
>
Bjorn Helgaas Dec. 11, 2020, 11:21 p.m. UTC | #2
On Fri, Dec 11, 2020 at 09:17:35PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> 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.
> 
> Link: https://lore.kernel.org/linux-acpi/1409ba0c-1580-dc09-e6fe-a0c9bcda6462@gmail.com/
> Reported-by: Daniel Scally <djrscally@gmail.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Applied with Daniel's Tested-by and Reviewed-by to pci/enumeration for
v5.11, thanks!

> ---
>  drivers/pci/pci-acpi.c |   20 +++++++++++++++++++-
>  1 file changed, 19 insertions(+), 1 deletion(-)
> 
> Index: linux-pm/drivers/pci/pci-acpi.c
> ===================================================================
> --- linux-pm.orig/drivers/pci/pci-acpi.c
> +++ linux-pm/drivers/pci/pci-acpi.c
> @@ -1162,14 +1162,32 @@ void acpi_pci_remove_bus(struct pci_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_dev->bus->parent)
> +		return NULL;
> +
> +	return adev;
>  }
>  
>  /**
> 
> 
>
diff mbox series

Patch

Index: linux-pm/drivers/pci/pci-acpi.c
===================================================================
--- linux-pm.orig/drivers/pci/pci-acpi.c
+++ linux-pm/drivers/pci/pci-acpi.c
@@ -1162,14 +1162,32 @@  void acpi_pci_remove_bus(struct pci_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_dev->bus->parent)
+		return NULL;
+
+	return adev;
 }
 
 /**