PCI: Wait for pending transactions to complete before 82599 FLR

Before initiating an FLR, we should wait for completion of any outstanding
non-posted requests.  See PCIe spec r3.0, sec 6.6.2.

This makes reset_intel_82599_sfp_virtfn() very similar to the generic
pcie_flr().  The only difference is that the 82599 doesn't report FLR
support in the VF Device Capability register.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 27 insertions, 1 deletions

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index aa77538c50c..7a451ff56ec 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -3081,10 +3081,36 @@ static int reset_intel_generic_dev(struct pci_dev *dev, int probe)
 
 static int reset_intel_82599_sfp_virtfn(struct pci_dev *dev, int probe)
 {
+        int i;
+        u16 status;
+
+        /*
+         * http://www.intel.com/content/dam/doc/datasheet/82599-10-gbe-controller-datasheet.pdf
+         *
+         * The 82599 supports FLR on VFs, but FLR support is reported only
+         * in the PF DEVCAP (sec 9.3.10.4), not in the VF DEVCAP (sec 9.5).
+         * Therefore, we can't use pcie_flr(), which checks the VF DEVCAP.
+         */
+
         if (probe)
                 return 0;
 
-        pcie_capability_write_word(dev, PCI_EXP_DEVCTL, PCI_EXP_DEVCTL_BCR_FLR);
+        /* Wait for Transaction Pending bit clean */
+        for (i = 0; i < 4; i++) {
+                if (i)
+                        msleep((1 << (i - 1)) * 100);
+
+                pcie_capability_read_word(dev, PCI_EXP_DEVSTA, &status);
+                if (!(status & PCI_EXP_DEVSTA_TRPND))
+                        goto clear;
+        }
+
+        dev_err(&dev->dev, "transaction is not cleared; "
+                        "proceeding with reset anyway\n");
+
+clear:
+        pcie_capability_set_word(dev, PCI_EXP_DEVCTL, PCI_EXP_DEVCTL_BCR_FLR);
+
         msleep(100);
 
         return 0;