Messages in this thread | | | Date | Tue, 11 Jul 2017 14:58:53 -0500 | From | Bjorn Helgaas <> | Subject | Re: [PATCH V3 1/2] PCI: Add Extended Tags quirk for Broadcom HT2100 Root Port |
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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
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