lkml.org 
[lkml]   [2017]   [Jul]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH V3 1/2] PCI: Add Extended Tags quirk for Broadcom HT2100 Root Port
    On Tue, Jul 11, 2017 at 11:25:33AM -0400, Sinan Kaya wrote:
    > All PCIe devices are expected to be able to handle 8-bit tags.
    > 'commit 60db3a4d8cc9 ("PCI: Enable PCIe Extended Tags if supported")'
    > enabled extended tags for all devices based on the spec direction.
    >
    > The Broadcom HT2100 seems to be having issues with handling
    > 8-bit tags. Mark it as broken.
    >
    > Reported-by: Wim ten Have <wim.ten.have@oracle.com>
    > Link: https://bugzilla.redhat.com/show_bug.cgi?id=1467674
    > Fixes: 60db3a4d8cc9 ("PCI: Enable PCIe Extended Tags if supported")
    > Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
    > ---
    > drivers/pci/quirks.c | 12 ++++++++++++
    > include/linux/pci.h | 1 +
    > 2 files changed, 13 insertions(+)
    >
    > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
    > index 085fb78..073d5dd 100644
    > --- a/drivers/pci/quirks.c
    > +++ b/drivers/pci/quirks.c
    > @@ -4664,3 +4664,15 @@ 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_exttags_completer(struct pci_dev *pdev)
    > +{
    > + /* This device cannot handle 256 tags as a completer */
    > + pdev->broken_exttags_completer = 1;

    I think we should print something here as a clue to the user.

    Wim, how did you find this problem originally? Seems like it could
    have been a hassle to track down. I wonder if we should log a message
    in pci_configure_extended_tags() when we change the setting (either to
    enable or disable). Maybe something in dmesg would have made it
    easier to find the problem.

    > +}
    > +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0140,
    > + quirk_exttags_completer);
    > +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0142,
    > + quirk_exttags_completer);
    > +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0144,
    > + quirk_exttags_completer);
    > diff --git a/include/linux/pci.h b/include/linux/pci.h
    > index 8039f9f..0b9f42d 100644
    > --- a/include/linux/pci.h
    > +++ b/include/linux/pci.h
    > @@ -376,6 +376,7 @@ struct pci_dev {
    > unsigned int irq_managed:1;
    > unsigned int has_secondary_link:1;
    > unsigned int non_compliant_bars:1; /* broken BARs; ignore them */
    > + unsigned int broken_exttags_completer:1;

    I think maybe we should put this bit in struct pci_host_bridge. Then
    the quirk could be something like this:

    static void quirk_ext_tags_broken(struct pci_dev *pdev)
    {
    struct pci_host_bridge *bridge = pci_find_host_bridge(pdev->bus);

    bridge->broken_ext_tags = 1;
    dev_info(&pdev->dev, "Extended Tag handling is broken\n");

    pci_walk_bus(bridge->bus, pci_configure_extended_tags, NULL);
    }

    and we could keep the current strategy of calling
    pci_configure_extended_tags() from pci_configure_device(), slightly
    modified like this:

    void pci_configure_extended_tags(struct pci_dev *dev, void *ign)
    {
    u32 cap;
    u16 ctl;
    int ret;
    struct pci_host_bridge *host;

    if (!pci_is_pcie(dev))
    return;

    ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &cap);
    if (ret)
    return;

    if (!(cap & PCI_EXP_DEVCAP_EXT_TAG))
    return;

    ret = pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &ctl);
    if (ret)
    return;

    host = pci_find_host_bridge(dev->bus);
    if (host->broken_ext_tags && (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;
    }

    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);
    }
    }

    I'm trying to avoid pci_walk_bus() because it's such a minefield as
    far as hot-added devices. I don't think we can avoid one in the
    quirk, to turn off extended tags for any devices we've already found,
    but I think we *can* avoid adding more in
    pcie_bus_configure_settings().

    > pci_dev_flags_t dev_flags;
    > atomic_t enable_cnt; /* pci_enable_device has been called */
    >
    > --
    > 1.9.1
    >
    >
    > _______________________________________________
    > linux-arm-kernel mailing list
    > linux-arm-kernel@lists.infradead.org
    > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

    \
     
     \ /
      Last update: 2017-07-11 22:00    [W:4.241 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site