Re: [PATCH v12 0/8] Add Error Disconnect Recover (EDR) support

[Bjorn Helgaas <helgaas@kernel.org>]

On Sun, Jan 12, 2020 at 02:43:54PM -0800, sathyanarayanan.kuppuswamy@linux.intel.com wrote:
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> 
> This patchset adds support for following features:
> 
> 1. Error Disconnect Recover (EDR) support.
> 2. _OSC based negotiation support for DPC.
> 
> You can find EDR spec in the following link.
> 
> https://members.pcisig.com/wg/PCI-SIG/document/12614

When you update this, please incorporate the changes I've made below.

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 134e20474dfd..0cb9df5462c3 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -491,7 +491,13 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
 			control |= OSC_PCI_EXPRESS_AER_CONTROL;
 	}
 
-	if (IS_ENABLED(CONFIG_PCIE_DPC))
+	/*
+	 * Per the Downstream Port Containment Related Enhancements ECN to
+	 * 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.
+	 */
+	if (IS_ENABLED(CONFIG_PCIE_DPC) && IS_ENABLED(CONFIG_PCIE_EDR))
 		control |= OSC_PCI_EXPRESS_DPC_CONTROL;
 
 	requested = control;
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 13086518de27..547089361d4d 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -103,8 +103,7 @@ int acpi_get_rc_resources(struct device *dev, const char *hid, u16 segment,
 }
 #endif
 
-#if defined(CONFIG_PCIE_DPC) && defined(CONFIG_ACPI)
-
+#if defined(CONFIG_PCIE_DPC)
 /*
  * _DSM wrapper function to enable/disable DPC port.
  * @dpc   : DPC device structure
@@ -124,14 +123,15 @@ int acpi_enable_dpc_port(struct pci_dev *pdev, acpi_handle handle, bool enable)
 	argv4.package.count = 1;
 	argv4.package.elements = &req;
 
-	/* As per PCI firmware specification r3.2 Downstream Port Containment
-	 * Related Enhancements ECN, sec 4.6.12, EDR_PORT_ENABLE_DSM is
-	 * optional and hence if its not implemented return success.
+	/*
+	 * Per the Downstream Port Containment Related Enhancements ECN to
+	 * the PCI Firmware Specification r3.2, sec 4.6.12,
+	 * EDR_PORT_ENABLE_DSM is optional.  Return success if it's not
+	 * implemented.
 	 */
-	obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 5,
-				EDR_PORT_ENABLE_DSM, &argv4);
+	obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 5, EDR_PORT_ENABLE_DSM, &argv4);
 	if (!obj)
-		return status;
+		return 0;
 
 	if (obj->type != ACPI_TYPE_INTEGER || obj->integer.value != enable)
 		status = -EIO;
@@ -152,8 +152,7 @@ struct pci_dev *acpi_locate_dpc_port(struct pci_dev *pdev, acpi_handle handle)
 	union acpi_object *obj;
 	u16 port;
 
-	obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 5,
-				EDR_PORT_LOCATE_DSM, NULL);
+	obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 5, EDR_PORT_LOCATE_DSM, NULL);
 	if (!obj)
 		return pci_dev_get(pdev);
 
@@ -165,8 +164,8 @@ struct pci_dev *acpi_locate_dpc_port(struct pci_dev *pdev, acpi_handle handle)
 	/*
 	 * Firmware returns DPC port BDF details in following format:
 	 *	15:8 = bus
-	 *	7:3 = device
-	 *	2:0 = function
+	 *	 7:3 = device
+	 *	 2:0 = function
 	 */
 	port = obj->integer.value;
 
@@ -181,11 +180,11 @@ struct pci_dev *acpi_locate_dpc_port(struct pci_dev *pdev, acpi_handle handle)
  * @dpc   : DPC device structure.
  * @status: Status of EDR event.
  */
-int acpi_send_edr_status(struct pci_dev *pdev,  acpi_handle handle, u16 status)
+int acpi_send_edr_status(struct pci_dev *pdev, acpi_handle handle, u16 status)
 {
 	u32 ost_status;
 
-	pci_dbg(pdev, "Sending EDR status :%x\n", status);
+	pci_dbg(pdev, "Sending EDR status: %#x\n", status);
 
 	ost_status =  PCI_DEVID(pdev->bus->number, pdev->devfn);
 	ost_status = (ost_status << 16) | status;
@@ -198,8 +197,7 @@ int acpi_send_edr_status(struct pci_dev *pdev,  acpi_handle handle, u16 status)
 
 	return 0;
 }
-
-#endif /* CONFIG_PCIE_DPC && CONFIG_ACPI */
+#endif /* CONFIG_PCIE_DPC */
 
 phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle)
 {
diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig
index 2db8a3109cb5..772b1f4cb19e 100644
--- a/drivers/pci/pcie/Kconfig
+++ b/drivers/pci/pcie/Kconfig
@@ -143,10 +143,10 @@ config PCIE_BW
 
 config PCIE_EDR
 	bool "PCI Express Error Disconnect Recover support"
-	default n
 	depends on PCIE_DPC && ACPI
 	help
-	  This options adds Error Disconnect Recover support as specified
-	  in PCI firmware specification v3.2 Downstream Port Containment
-	  Related Enhancements ECN. Enable this if you want to support hybrid
-	  DPC model which uses both firmware and OS to implement DPC.
+	  This option adds Error Disconnect Recover support as specified
+	  in the Downstream Port Containment Related Enhancements ECN to
+	  the PCI Firmware Specification r3.2.  Enable this if you want to
+	  support hybrid DPC model which uses both firmware and OS to
+	  implement DPC.
diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
index 49e020d46ea1..292ce4b69e7a 100644
--- a/drivers/pci/pcie/dpc.c
+++ b/drivers/pci/pcie/dpc.c
@@ -79,7 +79,7 @@ void pci_save_dpc_state(struct pci_dev *dev)
 
 	/*
 	 * If DPC is controlled by firmware then save/restore tasks are also
-	 * controller by firmware. So skip rest of the function if DPC is
+	 * controlled by firmware. So skip rest of the function if DPC is
 	 * controlled by firmware.
 	 */
 	if (dpc->edr_enabled)
@@ -108,7 +108,7 @@ void pci_restore_dpc_state(struct pci_dev *dev)
 
 	/*
 	 * If DPC is controlled by firmware then save/restore tasks are also
-	 * controller by firmware. So skip rest of the function if DPC is
+	 * controlled by firmware. So skip rest of the function if DPC is
 	 * controlled by firmware.
 	 */
 	if (dpc->edr_enabled)
@@ -331,14 +331,13 @@ static void dpc_error_resume(struct pci_dev *dev)
 }
 
 #ifdef CONFIG_ACPI
-
 static void edr_handle_event(acpi_handle handle, u32 event, void *data)
 {
-	struct dpc_dev *dpc = (struct dpc_dev *) data;
+	struct dpc_dev *dpc = data;
 	struct pci_dev *pdev = dpc->dev->port;
 	u16 status;
 
-	pci_info(pdev, "ACPI event %x received\n", event);
+	pci_info(pdev, "ACPI event %#x received\n", event);
 
 	if (event != ACPI_NOTIFY_DISCONNECT_RECOVER)
 		return;
@@ -375,7 +374,7 @@ static void edr_handle_event(acpi_handle handle, u32 event, void *data)
 		pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS,
 				     &status);
 		if (!(status & PCI_EXP_DPC_STATUS_TRIGGER)) {
-			pci_err(pdev, "Invalid DPC trigger %x\n", status);
+			pci_err(pdev, "Invalid DPC trigger %#010x\n", status);
 			goto edr_unlock;
 		}
 		dpc_process_error(dpc);
@@ -391,7 +390,7 @@ static void edr_handle_event(acpi_handle handle, u32 event, void *data)
 		status = 0x81;
 
 	/* Use ACPI handle of DPC event device for sending EDR status */
-	dpc = (struct dpc_dev *) data;
+	dpc = data;
 
 	acpi_send_edr_status(pdev, dpc->adev->handle, status);
 
@@ -400,7 +399,6 @@ static void edr_handle_event(acpi_handle handle, u32 event, void *data)
 done:
 	pci_dev_put(pdev);
 }
-
 #endif
 
 #define FLAG(x, y) (((x) & (y)) ? '+' : '-')
@@ -426,11 +424,12 @@ static int dpc_probe(struct pcie_device *dev)
 	mutex_init(&dpc->edr_lock);
 
 	/*
-	 * As per PCIe spec r5.0, implementation note titled "Determination
+	 * PCIe r5.0, sec 6.2.10, implementation note titled "Determination
 	 * of DPC Control", to avoid conflicts over whether platform
 	 * firmware or the operating system have control of DPC, it is
-	 * recommended that platform firmware and operating systems always link
-	 * the control of DPC to the control of Advanced Error Reporting.
+	 * recommended that platform firmware and operating systems always
+	 * link the control of DPC to the control of Advanced Error
+	 * Reporting.
 	 *
 	 * So use AER FF mode check API pcie_aer_get_firmware_first() to decide
 	 * whether DPC is controlled by software or firmware.
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 0b7c63c7888d..d0739e90f4e7 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -511,8 +511,8 @@ struct pci_host_bridge {
 	unsigned int	native_pme:1;		/* OS may use PCIe PME */
 	unsigned int	native_ltr:1;		/* OS may use PCIe LTR */
 	unsigned int	native_dpc:1;		/* OS may use PCIe DPC */
-
 	unsigned int	preserve_config:1;	/* Preserve FW resource setup */
+
 	/* Resource alignment requirements */
 	resource_size_t (*align_resource)(struct pci_dev *dev,
 			const struct resource *res,