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Date:      Fri, 5 Aug 2016 18:41:51 +0000 (UTC)
From:      John Baldwin <jhb@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org
Subject:   svn commit: r303781 - stable/11/sys/dev/pci
Message-ID:  <201608051841.u75Ifp6M093873@repo.freebsd.org>

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Author: jhb
Date: Fri Aug  5 18:41:51 2016
New Revision: 303781
URL: https://svnweb.freebsd.org/changeset/base/303781

Log:
  MFC 303497,303559,303645: Disable PCI-e hotplug on bridges with power
  controllers.
  
  303497:
  Add a loader tunable (hw.pci.enable_pcie_hp) to disable PCI-e HotPlug.
  
  Some systems and/or devices (such as riser cards) do not include a
  non-compliant implementation of PCI-e HotPlug that can result in devices
  not being attached (e.g. the HotPlug code might assume that a card is
  being unplugged and will power the slot off and detach it).  This
  tunable can be set to 0 to disable support for PCI-e HotPlug ignoring
  the incorrect HotPlug state on these slots.
  
  303559:
  Try to declare _hw_pci for all sysctl cases needed after r303497.
  
  303645:
  Disable PCI hotplug support for slots with power controllers.
  
  After further review of the spec, I do not think the current HotPlug
  code handles slots with power controllers correctly.  In particular,
  the power state of the slot is to be inferred from other events, not
  from examining the state of the power control bit in SLOT_CTL.  For now,
  disable PCI hotplug support on such slots.
  
  PR:		211081
  Approved by:	re (gjb)

Modified:
  stable/11/sys/dev/pci/pci_pci.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/dev/pci/pci_pci.c
==============================================================================
--- stable/11/sys/dev/pci/pci_pci.c	Fri Aug  5 17:49:13 2016	(r303780)
+++ stable/11/sys/dev/pci/pci_pci.c	Fri Aug  5 18:41:51 2016	(r303781)
@@ -128,9 +128,11 @@ static devclass_t pcib_devclass;
 DEFINE_CLASS_0(pcib, pcib_driver, pcib_methods, sizeof(struct pcib_softc));
 DRIVER_MODULE(pcib, pci, pcib_driver, pcib_devclass, NULL, NULL);
 
-#ifdef NEW_PCIB
+#if defined(NEW_PCIB) || defined(PCI_HP)
 SYSCTL_DECL(_hw_pci);
+#endif
 
+#ifdef NEW_PCIB
 static int pci_clear_pcib;
 SYSCTL_INT(_hw_pci, OID_AUTO, clear_pcib, CTLFLAG_RDTUN, &pci_clear_pcib, 0,
     "Clear firmware-assigned resources for PCI-PCI bridge I/O windows.");
@@ -907,11 +909,19 @@ pcib_set_mem_decode(struct pcib_softc *s
 /*
  * PCI-express HotPlug support.
  */
+static int pci_enable_pcie_hp = 1;
+SYSCTL_INT(_hw_pci, OID_AUTO, enable_pcie_hp, CTLFLAG_RDTUN,
+    &pci_enable_pcie_hp, 0,
+    "Enable support for native PCI-express HotPlug.");
+
 static void
 pcib_probe_hotplug(struct pcib_softc *sc)
 {
 	device_t dev;
 
+	if (!pci_enable_pcie_hp)
+		return;
+
 	dev = sc->dev;
 	if (pci_find_cap(dev, PCIY_EXPRESS, NULL) != 0)
 		return;
@@ -922,6 +932,13 @@ pcib_probe_hotplug(struct pcib_softc *sc
 	sc->pcie_link_cap = pcie_read_config(dev, PCIER_LINK_CAP, 4);
 	sc->pcie_slot_cap = pcie_read_config(dev, PCIER_SLOT_CAP, 4);
 
+	/*
+	 * XXX: Handling of slots with a power controller needs to be
+	 * reexamined.  Ignore hotplug on such slots for now.
+	 */
+	if (sc->pcie_slot_cap & PCIEM_SLOT_CAP_PCP)
+		return;
+	
 	if (sc->pcie_slot_cap & PCIEM_SLOT_CAP_HPC)
 		sc->flags |= PCIB_HOTPLUG;
 }



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