PCI: Correct error reporting with PCIe failed link retraining

Only return successful completion status from pcie_failed_link_retrain() if
retraining has actually been done, preventing excessive delays from being
triggered at call sites in a hope that communication will finally be
established with the downstream device where in fact nothing has been done
about the link in question that would justify such a hope.

Fixes: a89c82249c37 ("PCI: Work around PCIe link training failures")
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2408091133260.61955@angie.orcam.me.uk
Reported-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/aa2d1c4e-9961-d54a-00c7-ddf8e858a9b0@linux.intel.com/
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: <stable@vger.kernel.org> # v6.5+

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index ee86793109ff7efc4d2a0326d1c9be439dbbc3a0..4d5483e9f63f438ba4b76a7f18428ca2bc8c92e4 100644 (file)
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -78,7 +78,8 @@
  * again to remove any residual state, ignoring the result as it's supposed
  * to fail anyway.
  *
- * Return TRUE if the link has been successfully retrained, otherwise FALSE.
+ * Return TRUE if the link has been successfully retrained.  Return FALSE
+ * if retraining was not needed or we attempted a retrain and it failed.
  */
 bool pcie_failed_link_retrain(struct pci_dev *dev)
 {
@@ -87,6 +88,7 @@ bool pcie_failed_link_retrain(struct pci_dev *dev)
                {}
        };
        u16 lnksta, lnkctl2;
+       bool ret = false;
 
        if (!pci_is_pcie(dev) || !pcie_downstream_port(dev) ||
            !pcie_cap_has_lnkctl2(dev) || !dev->link_active_reporting)
@@ -104,7 +106,8 @@ bool pcie_failed_link_retrain(struct pci_dev *dev)
                lnkctl2 |= PCI_EXP_LNKCTL2_TLS_2_5GT;
                pcie_capability_write_word(dev, PCI_EXP_LNKCTL2, lnkctl2);
 
-               if (pcie_retrain_link(dev, false)) {
+               ret = pcie_retrain_link(dev, false) == 0;
+               if (!ret) {
                        pci_info(dev, "retraining failed\n");
                        pcie_capability_write_word(dev, PCI_EXP_LNKCTL2,
                                                   oldlnkctl2);
@@ -126,13 +129,14 @@ bool pcie_failed_link_retrain(struct pci_dev *dev)
                lnkctl2 |= lnkcap & PCI_EXP_LNKCAP_SLS;
                pcie_capability_write_word(dev, PCI_EXP_LNKCTL2, lnkctl2);
 
-               if (pcie_retrain_link(dev, false)) {
+               ret = pcie_retrain_link(dev, false) == 0;
+               if (!ret) {
                        pci_info(dev, "retraining failed\n");
                        return false;
                }
        }
 
-       return true;
+       return ret;
 }
 
 static ktime_t fixup_debug_start(struct pci_dev *dev,