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authorStefan Mätje <stefan.maetje@esd.eu>2019-03-29 18:07:35 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-05-25 18:26:53 +0200
commitd0a3f25d63855d37d453ca009483aeae08b1c1dc (patch)
treeff4b3f029a5008f56bb9dc4b9721930efbda5e90 /drivers/pci
parent1c38a7b6845ed04e2fb0cf08d70c1a12ab753c41 (diff)
PCI: Work around Pericom PCIe-to-PCI bridge Retrain Link erratum
commit 4ec73791a64bab25cabf16a6067ee478692e506d upstream. Due to an erratum in some Pericom PCIe-to-PCI bridges in reverse mode (conventional PCI on primary side, PCIe on downstream side), the Retrain Link bit needs to be cleared manually to allow the link training to complete successfully. If it is not cleared manually, the link training is continuously restarted and no devices below the PCI-to-PCIe bridge can be accessed. That means drivers for devices below the bridge will be loaded but won't work and may even crash because the driver is only reading 0xffff. See the Pericom Errata Sheet PI7C9X111SLB_errata_rev1.2_102711.pdf for details. Devices known as affected so far are: PI7C9X110, PI7C9X111SL, PI7C9X130. Add a new flag, clear_retrain_link, in struct pci_dev. Quirks for affected devices set this bit. Note that pcie_retrain_link() lives in aspm.c because that's currently the only place we use it, but this erratum is not specific to ASPM, and we may retrain links for other reasons in the future. Signed-off-by: Stefan Mätje <stefan.maetje@esd.eu> [bhelgaas: apply regardless of CONFIG_PCIEASPM] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> CC: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/pci')
-rw-r--r--drivers/pci/pcie/aspm.c9
-rw-r--r--drivers/pci/quirks.c17
2 files changed, 26 insertions, 0 deletions
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index e83f438b036b..b12fe65d07f8 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -181,6 +181,15 @@ static bool pcie_retrain_link(struct pcie_link_state *link)
pcie_capability_read_word(parent, PCI_EXP_LNKCTL, &reg16);
reg16 |= PCI_EXP_LNKCTL_RL;
pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
+ if (parent->clear_retrain_link) {
+ /*
+ * Due to an erratum in some devices the Retrain Link bit
+ * needs to be cleared again manually to allow the link
+ * training to succeed.
+ */
+ reg16 &= ~PCI_EXP_LNKCTL_RL;
+ pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
+ }
/* Wait for link training end. Break out after waiting for timeout */
start_jiffies = jiffies;
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 54fea9ab9d81..f474899073e0 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -2046,6 +2046,23 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x10f1, quirk_disable_aspm_l0s);
DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x10f4, quirk_disable_aspm_l0s);
DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x1508, quirk_disable_aspm_l0s);
+/*
+ * Some Pericom PCIe-to-PCI bridges in reverse mode need the PCIe Retrain
+ * Link bit cleared after starting the link retrain process to allow this
+ * process to finish.
+ *
+ * Affected devices: PI7C9X110, PI7C9X111SL, PI7C9X130. See also the
+ * Pericom Errata Sheet PI7C9X111SLB_errata_rev1.2_102711.pdf.
+ */
+static void quirk_enable_clear_retrain_link(struct pci_dev *dev)
+{
+ dev->clear_retrain_link = 1;
+ pci_info(dev, "Enable PCIe Retrain Link quirk\n");
+}
+DECLARE_PCI_FIXUP_HEADER(0x12d8, 0xe110, quirk_enable_clear_retrain_link);
+DECLARE_PCI_FIXUP_HEADER(0x12d8, 0xe111, quirk_enable_clear_retrain_link);
+DECLARE_PCI_FIXUP_HEADER(0x12d8, 0xe130, quirk_enable_clear_retrain_link);
+
static void fixup_rev1_53c810(struct pci_dev *dev)
{
u32 class = dev->class;