Merge branch 'pci/enumeration'

- Add PCI_EXT_CAP_ID_PL_32GT define (Ben Dooks)

- Propagate firmware node by calling device_set_node() for better
  modularity (Andy Shevchenko)

- Discover Data Link Layer Link Active Reporting earlier so quirks can take
  advantage of it (Maciej W. Rozycki)

- Use cached Data Link Layer Link Active Reporting capability in pciehp,
  powerpc/eeh, and mlx5 (Maciej W. Rozycki)

- Run quirk for devices that require OS to clear Retrain Link earlier, so
  later quirks can rely on it (Maciej W. Rozycki)

- Export pcie_retrain_link() for use outside ASPM (Maciej W. Rozycki)

- Add Data Link Layer Link Active Reporting as another way for
  pcie_retrain_link() to determine the link is up (Maciej W. Rozycki)

- Work around link training failures (especially on the ASMedia ASM2824
  switch) by training first at 2.5GT/s and then attempting higher rates
  (Maciej W. Rozycki)

* pci/enumeration:
  PCI: Add failed link recovery for device reset events
  PCI: Work around PCIe link training failures
  PCI: Use pcie_wait_for_link_status() in pcie_wait_for_link_delay()
  PCI: Add support for polling DLLLA to pcie_retrain_link()
  PCI: Export pcie_retrain_link() for use outside ASPM
  PCI: Export PCIe link retrain timeout
  PCI: Execute quirk_enable_clear_retrain_link() earlier
  PCI/ASPM: Factor out waiting for link training to complete
  PCI/ASPM: Avoid unnecessary pcie_link_state use
  PCI/ASPM: Use distinct local vars in pcie_retrain_link()
  net/mlx5: Rely on dev->link_active_reporting
  powerpc/eeh: Rely on dev->link_active_reporting
  PCI: pciehp: Rely on dev->link_active_reporting
  PCI: Initialize dev->link_active_reporting earlier
  PCI: of: Propagate firmware node by calling device_set_node()
  PCI: Add PCI_EXT_CAP_ID_PL_32GT define

# Conflicts:
#	drivers/pci/pcie/aspm.c

1 files changed, 96 insertions, 3 deletions

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index f4e2a88729fd..1c4f715537c1 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -33,6 +33,99 @@
 #include <linux/switchtec.h>
 #include "pci.h"
 
+/*
+ * Retrain the link of a downstream PCIe port by hand if necessary.
+ *
+ * This is needed at least where a downstream port of the ASMedia ASM2824
+ * Gen 3 switch is wired to the upstream port of the Pericom PI7C9X2G304
+ * Gen 2 switch, and observed with the Delock Riser Card PCI Express x1 >
+ * 2 x PCIe x1 device, P/N 41433, plugged into the SiFive HiFive Unmatched
+ * board.
+ *
+ * In such a configuration the switches are supposed to negotiate the link
+ * speed of preferably 5.0GT/s, falling back to 2.5GT/s.  However the link
+ * continues switching between the two speeds indefinitely and the data
+ * link layer never reaches the active state, with link training reported
+ * repeatedly active ~84% of the time.  Forcing the target link speed to
+ * 2.5GT/s with the upstream ASM2824 device makes the two switches talk to
+ * each other correctly however.  And more interestingly retraining with a
+ * higher target link speed afterwards lets the two successfully negotiate
+ * 5.0GT/s.
+ *
+ * With the ASM2824 we can rely on the otherwise optional Data Link Layer
+ * Link Active status bit and in the failed link training scenario it will
+ * be off along with the Link Bandwidth Management Status indicating that
+ * hardware has changed the link speed or width in an attempt to correct
+ * unreliable link operation.  For a port that has been left unconnected
+ * both bits will be clear.  So use this information to detect the problem
+ * rather than polling the Link Training bit and watching out for flips or
+ * at least the active status.
+ *
+ * Since the exact nature of the problem isn't known and in principle this
+ * could trigger where an ASM2824 device is downstream rather upstream,
+ * apply this erratum workaround to any downstream ports as long as they
+ * support Link Active reporting and have the Link Control 2 register.
+ * Restrict the speed to 2.5GT/s then with the Target Link Speed field,
+ * request a retrain and wait 200ms for the data link to go up.
+ *
+ * If this turns out successful and we know by the Vendor:Device ID it is
+ * safe to do so, then lift the restriction, letting the devices negotiate
+ * a higher speed.  Also check for a similar 2.5GT/s speed restriction the
+ * firmware may have already arranged and lift it with ports that already
+ * report their data link being up.
+ *
+ * Return TRUE if the link has been successfully retrained, otherwise FALSE.
+ */
+bool pcie_failed_link_retrain(struct pci_dev *dev)
+{
+	static const struct pci_device_id ids[] = {
+		{ PCI_VDEVICE(ASMEDIA, 0x2824) }, /* ASMedia ASM2824 */
+		{}
+	};
+	u16 lnksta, lnkctl2;
+
+	if (!pci_is_pcie(dev) || !pcie_downstream_port(dev) ||
+	    !pcie_cap_has_lnkctl2(dev) || !dev->link_active_reporting)
+		return false;
+
+	pcie_capability_read_word(dev, PCI_EXP_LNKCTL2, &lnkctl2);
+	pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &lnksta);
+	if ((lnksta & (PCI_EXP_LNKSTA_LBMS | PCI_EXP_LNKSTA_DLLLA)) ==
+	    PCI_EXP_LNKSTA_LBMS) {
+		pci_info(dev, "broken device, retraining non-functional downstream link at 2.5GT/s\n");
+
+		lnkctl2 &= ~PCI_EXP_LNKCTL2_TLS;
+		lnkctl2 |= PCI_EXP_LNKCTL2_TLS_2_5GT;
+		pcie_capability_write_word(dev, PCI_EXP_LNKCTL2, lnkctl2);
+
+		if (pcie_retrain_link(dev, false)) {
+			pci_info(dev, "retraining failed\n");
+			return false;
+		}
+
+		pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &lnksta);
+	}
+
+	if ((lnksta & PCI_EXP_LNKSTA_DLLLA) &&
+	    (lnkctl2 & PCI_EXP_LNKCTL2_TLS) == PCI_EXP_LNKCTL2_TLS_2_5GT &&
+	    pci_match_id(ids, dev)) {
+		u32 lnkcap;
+
+		pci_info(dev, "removing 2.5GT/s downstream link speed restriction\n");
+		pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnkcap);
+		lnkctl2 &= ~PCI_EXP_LNKCTL2_TLS;
+		lnkctl2 |= lnkcap & PCI_EXP_LNKCAP_SLS;
+		pcie_capability_write_word(dev, PCI_EXP_LNKCTL2, lnkctl2);
+
+		if (pcie_retrain_link(dev, false)) {
+			pci_info(dev, "retraining failed\n");
+			return false;
+		}
+	}
+
+	return true;
+}
+
 static ktime_t fixup_debug_start(struct pci_dev *dev,
 				 void (*fn)(struct pci_dev *dev))
 {
@@ -2420,9 +2513,9 @@ 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(PCI_VENDOR_ID_PERICOM, 0xe110, quirk_enable_clear_retrain_link);
-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_PERICOM, 0xe111, quirk_enable_clear_retrain_link);
-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_PERICOM, 0xe130, quirk_enable_clear_retrain_link);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_PERICOM, 0xe110, quirk_enable_clear_retrain_link);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_PERICOM, 0xe111, quirk_enable_clear_retrain_link);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_PERICOM, 0xe130, quirk_enable_clear_retrain_link);
 
 static void fixup_rev1_53c810(struct pci_dev *dev)
 {