svn commit: r334365 - head/sys/dev/pci

[Justin Hibbits]

Author: jhibbits
Date: Wed May 30 02:41:47 2018
New Revision: 334365
URL: https://svnweb.freebsd.org/changeset/base/334365

Log:
  Restrict PCIe maxslots to 0, instead of PCI_SLOTMAX
  
  Summary:
  PCIe only permits 1 device on an endpoint, so some devices ignore the device
  part of B:D:F probing.  Although ARI likely fixes this, not all platforms
  support ARI completely or correctly, so some devices end up showing up 32
  times on the bus.
  
  This was found during bringup of POWER9/Talos, and has been tested on POWER9
  and POWER8 hardware.
  
  Reviewed by:	leitao
  Differential Revision: https://reviews.freebsd.org/D15461

Modified:
  head/sys/dev/pci/pci_pci.c

Modified: head/sys/dev/pci/pci_pci.c
==============================================================================
--- head/sys/dev/pci/pci_pci.c	Wed May 30 02:26:36 2018	(r334364)
+++ head/sys/dev/pci/pci_pci.c	Wed May 30 02:41:47 2018	(r334365)
@@ -2545,6 +2545,20 @@ pcib_enable_ari(struct pcib_softc *sc, uint32_t pcie_p
 int
 pcib_maxslots(device_t dev)
 {
+	uint32_t pcie_pos;
+	uint16_t val;
+
+	/*
+	 * If this is a PCIe rootport or downstream switch port, there's only
+	 * one slot permitted.
+	 */
+	if (pci_find_cap(dev, PCIY_EXPRESS, &pcie_pos) == 0) {
+		val = pci_read_config(dev, pcie_pos + PCIER_FLAGS, 2);
+		val &= PCIEM_FLAGS_TYPE;
+		if (val == PCIEM_TYPE_ROOT_PORT ||
+		    val == PCIEM_TYPE_DOWNSTREAM_PORT)
+			return (0);
+	}
 	return (PCI_SLOTMAX);
 }
 
@@ -2558,7 +2572,7 @@ pcib_ari_maxslots(device_t dev)
 	if (sc->flags & PCIB_ENABLE_ARI)
 		return (PCIE_ARI_SLOTMAX);
 	else
-		return (PCI_SLOTMAX);
+		return (pcib_maxslots(dev));
 }
 
 static int