[PATCH 3/4] PCI/ACPI: Request DPC control only together with AER control

[Kuppuswamy Sathyanarayanan]

PCI Firmware r3.3, sec 4.5.2.4, requires the OS to request AER control
when it requests DPC control.  calculate_control() requests DPC control
whenever CONFIG_PCIE_DPC is enabled, even if it does not request AER
control, e.g., with "pci=noaer" or when MSI is disabled.

Request DPC control only if AER control is also requested.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
---
 drivers/acpi/pci_root.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index b0e0b33e3254..5c674d5b6bb8 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -516,8 +516,12 @@ static u32 calculate_control(void)
 	 * the PCI Firmware Spec, r3.2, sec 4.5.1, table 4-5,
 	 * OSC_PCI_EXPRESS_DPC_CONTROL indicates the OS supports both DPC
 	 * and EDR.  EDR is always built with DPC on ACPI systems.
+	 *
+	 * PCI Firmware r3.3, sec 4.5.2.4, requires the OS to request AER
+	 * control while requesting DPC control.
 	 */
-	if (IS_ENABLED(CONFIG_PCIE_DPC))
+	if (IS_ENABLED(CONFIG_PCIE_DPC) &&
+	    (control & OSC_PCI_EXPRESS_AER_CONTROL))
 		control |= OSC_PCI_EXPRESS_DPC_CONTROL;
 
 	return control;
-- 
2.43.0