From 91295d79d65892eabd02a2a75fd4ac88197d17a1 Mon Sep 17 00:00:00 2001
From: Sinan Kaya <okaya@codeaurora.org>
Date: Tue, 27 Feb 2018 14:14:08 -0600
Subject: [PATCH] PCI: Handle FLR failure and allow other reset types
Git-commit: 91295d79d65892eabd02a2a75fd4ac88197d17a1
Patch-mainline: v4.17-rc1
References: FATE#326145

pci_flr_wait() and pci_af_flr() functions assume graceful return even
though the device is inaccessible under error conditions.

Return -ENOTTY in error cases so that __pci_reset_function_locked() can
try other reset types if AF_FLR/FLR reset fails.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/pci/pci.c   |   18 ++++++++++--------
 include/linux/pci.h |    2 +-
 2 files changed, 11 insertions(+), 9 deletions(-)

--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3946,7 +3946,7 @@ int pci_wait_for_pending_transaction(str
 }
 EXPORT_SYMBOL(pci_wait_for_pending_transaction);
 
-static void pci_flr_wait(struct pci_dev *dev)
+static int pci_flr_wait(struct pci_dev *dev)
 {
 	int delay = 1, timeout = 60000;
 	u32 id;
@@ -3975,7 +3975,7 @@ static void pci_flr_wait(struct pci_dev
 		if (delay > timeout) {
 			pci_warn(dev, "not ready %dms after FLR; giving up\n",
 				 100 + delay - 1);
-			return;
+			return -ENOTTY;
 		}
 
 		if (delay > 1000)
@@ -3989,6 +3989,8 @@ static void pci_flr_wait(struct pci_dev
 
 	if (delay > 1000)
 		pci_info(dev, "ready %dms after FLR\n", 100 + delay - 1);
+
+	return 0;
 }
 
 /**
@@ -4017,13 +4019,13 @@ static bool pcie_has_flr(struct pci_dev
  * device supports FLR before calling this function, e.g. by using the
  * pcie_has_flr() helper.
  */
-void pcie_flr(struct pci_dev *dev)
+int pcie_flr(struct pci_dev *dev)
 {
 	if (!pci_wait_for_pending_transaction(dev))
 		pci_err(dev, "timed out waiting for pending transaction; performing function level reset anyway\n");
 
 	pcie_capability_set_word(dev, PCI_EXP_DEVCTL, PCI_EXP_DEVCTL_BCR_FLR);
-	pci_flr_wait(dev);
+	return pci_flr_wait(dev);
 }
 EXPORT_SYMBOL_GPL(pcie_flr);
 
@@ -4056,8 +4058,7 @@ static int pci_af_flr(struct pci_dev *de
 		pci_err(dev, "timed out waiting for pending transaction; performing AF function level reset anyway\n");
 
 	pci_write_config_byte(dev, pos + PCI_AF_CTRL, PCI_AF_CTRL_FLR);
-	pci_flr_wait(dev);
-	return 0;
+	return pci_flr_wait(dev);
 }
 
 /**
@@ -4329,8 +4330,9 @@ int __pci_reset_function_locked(struct p
 	if (rc != -ENOTTY)
 		return rc;
 	if (pcie_has_flr(dev)) {
-		pcie_flr(dev);
-		return 0;
+		rc = pcie_flr(dev);
+		if (rc != -ENOTTY)
+			return rc;
 	}
 	rc = pci_af_flr(dev, 0);
 	if (rc != -ENOTTY)
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1089,7 +1089,7 @@ u32 pcie_bandwidth_available(struct pci_
 			     enum pci_bus_speed *speed,
 			     enum pcie_link_width *width);
 void pcie_print_link_status(struct pci_dev *dev);
-void pcie_flr(struct pci_dev *dev);
+int pcie_flr(struct pci_dev *dev);
 int __pci_reset_function(struct pci_dev *dev);
 int __pci_reset_function_locked(struct pci_dev *dev);
 int pci_reset_function(struct pci_dev *dev);