[PATCH 2/5] PCI: handle FLR failure and allow other reset types

Sinan Kaya
2017-09-24T00:18:01Z

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

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 23681f4..27ec45d 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3820,7 +3820,7 @@ int pci_wait_for_pending_transaction(struct pci_dev *dev)
}
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;
@@ -3849,7 +3849,7 @@ static void pci_flr_wait(struct pci_dev *dev)
if (delay > timeout) {
dev_warn(&dev->dev, "not ready %dms after FLR; giving up\n",
100 + delay - 1);
- return;
+ return -ENOTTY;
}

if (delay > 1000)
@@ -3863,6 +3863,8 @@ static void pci_flr_wait(struct pci_dev *dev)

if (delay > 1000)
dev_info(&dev->dev, "ready %dms after FLR\n", 100 + delay - 1);
+
+ return 0;
}

/**
@@ -3891,13 +3893,13 @@ static bool pcie_has_flr(struct pci_dev *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))
dev_err(&dev->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);

@@ -3930,8 +3932,7 @@ static int pci_af_flr(struct pci_dev *dev, int probe)
dev_err(&dev->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);
}

/**
@@ -4203,8 +4204,9 @@ int __pci_reset_function_locked(struct pci_dev *dev)
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)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index f68c58a..104224f7 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1088,7 +1088,7 @@ static inline int pci_is_managed(struct pci_dev *pdev)
int pcie_set_mps(struct pci_dev *dev, int mps);
int pcie_get_minimum_link(struct pci_dev *dev, enum pci_bus_speed *speed,
enum pcie_link_width *width);
-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);
--
1.9.1