Merge branch 'pci/edr'

- Specify Revision 6 of the "Enable DPC" _DSM function to match the
  implementation (Kuppuswamy Sathyanarayanan)

- Check for failure of the "Locate Port" _DSM function (Kuppuswamy
  Sathyanarayanan)

* pci/edr:
  PCI/EDR: Align EDR_PORT_LOCATE_DSM with PCI Firmware r3.3
  PCI/EDR: Align EDR_PORT_DPC_ENABLE_DSM with PCI Firmware r3.3

1 files changed, 17 insertions, 11 deletions

diff --git a/drivers/pci/pcie/edr.c b/drivers/pci/pcie/edr.c
index 5f4914d313a1..e86298dbbcff 100644
--- a/drivers/pci/pcie/edr.c
+++ b/drivers/pci/pcie/edr.c
@@ -32,10 +32,10 @@ static int acpi_enable_dpc(struct pci_dev *pdev)
 	int status = 0;
 
 	/*
-	 * Behavior when calling unsupported _DSM functions is undefined,
-	 * so check whether EDR_PORT_DPC_ENABLE_DSM is supported.
+	 * Per PCI Firmware r3.3, sec 4.6.12, EDR_PORT_DPC_ENABLE_DSM is
+	 * optional. Return success if it's not implemented.
 	 */
-	if (!acpi_check_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
+	if (!acpi_check_dsm(adev->handle, &pci_acpi_dsm_guid, 6,
 			    1ULL << EDR_PORT_DPC_ENABLE_DSM))
 		return 0;
 
@@ -46,12 +46,7 @@ static int acpi_enable_dpc(struct pci_dev *pdev)
 	argv4.package.count = 1;
 	argv4.package.elements = &req;
 
-	/*
-	 * Per Downstream Port Containment Related Enhancements ECN to PCI
-	 * Firmware Specification r3.2, sec 4.6.12, EDR_PORT_DPC_ENABLE_DSM is
-	 * optional.  Return success if it's not implemented.
-	 */
-	obj = acpi_evaluate_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
+	obj = acpi_evaluate_dsm(adev->handle, &pci_acpi_dsm_guid, 6,
 				EDR_PORT_DPC_ENABLE_DSM, &argv4);
 	if (!obj)
 		return 0;
@@ -85,8 +80,9 @@ static struct pci_dev *acpi_dpc_port_get(struct pci_dev *pdev)
 	u16 port;
 
 	/*
-	 * Behavior when calling unsupported _DSM functions is undefined,
-	 * so check whether EDR_PORT_DPC_ENABLE_DSM is supported.
+	 * If EDR_PORT_LOCATE_DSM is not implemented under the target of
+	 * EDR, the target is the port that experienced the containment
+	 * event (PCI Firmware r3.3, sec 4.6.13).
 	 */
 	if (!acpi_check_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
 			    1ULL << EDR_PORT_LOCATE_DSM))
@@ -104,6 +100,16 @@ static struct pci_dev *acpi_dpc_port_get(struct pci_dev *pdev)
 	}
 
 	/*
+	 * Bit 31 represents the success/failure of the operation. If bit
+	 * 31 is set, the operation failed.
+	 */
+	if (obj->integer.value & BIT(31)) {
+		ACPI_FREE(obj);
+		pci_err(pdev, "Locate Port _DSM failed\n");
+		return NULL;
+	}
+
+	/*
 	 * Firmware returns DPC port BDF details in following format:
 	 *	15:8 = bus
 	 *	 7:3 = device