PCI: Mark Broadcom HT2100 Root Port Extended Tags as broken

Per PCIe r3.1, sec 2.2.6.2 and 7.8.4, a Requester may not use 8-bit Tags
unless its Extended Tag Field Enable is set, but all Receivers/Completers
must handle 8-bit Tags correctly regardless of their Extended Tag Field
Enable.

Some devices do not handle 8-bit Tags as Completers, so add a quirk for
them.  If we find such a device, we disable Extended Tags for the entire
hierarchy to make peer-to-peer DMA possible.

The Broadcom HT2100 seems to have issues with handling 8-bit tags.  Mark it
as broken.

The pci_walk_bus() in the quirk handles devices we've enumerated in the
past, and pci_configure_device() handles devices we enumerate in the
future.

Fixes: 60db3a4d8cc9 ("PCI: Enable PCIe Extended Tags if supported")
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1467674
Reported-and-tested-by: Wim ten Have <wim.ten.have@oracle.com>
Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
[bhelgaas: changelog, tweak messages, rename bit and quirk]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 22e0617..a6560c9 100644 (file)
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -235,6 +235,7 @@ enum pci_bar_type {
        pci_bar_mem64,          /* A 64-bit memory BAR */
 };
 
+int pci_configure_extended_tags(struct pci_dev *dev, void *ign);
 bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *pl,
                                int crs_timeout);
 int pci_setup_device(struct pci_dev *dev);

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index c31310d..c81c983 100644 (file)
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1745,21 +1745,50 @@ static void program_hpp_type2(struct pci_dev *dev, struct hpp_type2 *hpp)
         */
 }
 
-static void pci_configure_extended_tags(struct pci_dev *dev)
+int pci_configure_extended_tags(struct pci_dev *dev, void *ign)
 {
-       u32 dev_cap;
+       struct pci_host_bridge *host;
+       u32 cap;
+       u16 ctl;
        int ret;
 
        if (!pci_is_pcie(dev))
-               return;
+               return 0;
 
-       ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &dev_cap);
+       ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &cap);
        if (ret)
-               return;
+               return 0;
+
+       if (!(cap & PCI_EXP_DEVCAP_EXT_TAG))
+               return 0;
 
-       if (dev_cap & PCI_EXP_DEVCAP_EXT_TAG)
+       ret = pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &ctl);
+       if (ret)
+               return 0;
+
+       host = pci_find_host_bridge(dev->bus);
+       if (!host)
+               return 0;
+
+       /*
+        * If some device in the hierarchy doesn't handle Extended Tags
+        * correctly, make sure they're disabled.
+        */
+       if (host->no_ext_tags) {
+               if (ctl & PCI_EXP_DEVCTL_EXT_TAG) {
+                       dev_info(&dev->dev, "disabling Extended Tags\n");
+                       pcie_capability_clear_word(dev, PCI_EXP_DEVCTL,
+                                                  PCI_EXP_DEVCTL_EXT_TAG);
+               }
+               return 0;
+       }
+
+       if (!(ctl & PCI_EXP_DEVCTL_EXT_TAG)) {
+               dev_info(&dev->dev, "enabling Extended Tags\n");
                pcie_capability_set_word(dev, PCI_EXP_DEVCTL,
                                         PCI_EXP_DEVCTL_EXT_TAG);
+       }
+       return 0;
 }
 
 static void pci_configure_device(struct pci_dev *dev)
@@ -1768,7 +1797,7 @@ static void pci_configure_device(struct pci_dev *dev)
        int ret;
 
        pci_configure_mps(dev);
-       pci_configure_extended_tags(dev);
+       pci_configure_extended_tags(dev, NULL);
 
        memset(&hpp, 0, sizeof(hpp));
        ret = pci_get_hp_params(dev, &hpp);

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 6967c6b..f135765 100644 (file)
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -4681,3 +4681,19 @@ static void quirk_intel_no_flr(struct pci_dev *dev)
 }
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1502, quirk_intel_no_flr);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1503, quirk_intel_no_flr);
+
+static void quirk_no_ext_tags(struct pci_dev *pdev)
+{
+       struct pci_host_bridge *bridge = pci_find_host_bridge(pdev->bus);
+
+       if (!bridge)
+               return;
+
+       bridge->no_ext_tags = 1;
+       dev_info(&pdev->dev, "disabling Extended Tags (this device can't handle them)\n");
+
+       pci_walk_bus(bridge->bus, pci_configure_extended_tags, NULL);
+}
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0140, quirk_no_ext_tags);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0142, quirk_no_ext_tags);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0144, quirk_no_ext_tags);

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 4869e66..3b968d4 100644 (file)
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -451,6 +451,7 @@ struct pci_host_bridge {
        void *release_data;
        struct msi_controller *msi;
        unsigned int ignore_reset_delay:1;      /* for entire hierarchy */
+       unsigned int no_ext_tags:1;             /* no Extended Tags */
        /* Resource alignment requirements */
        resource_size_t (*align_resource)(struct pci_dev *dev,
                        const struct resource *res,