A hardware quirk in P320h/P420m interfere with PCIe transactions on some AMD chipsets, making P320h/P420m unusable. This workaround is to disable ERO and NoSnoop bits in the parent and root complex for normal functioning of these devices
NOTE: This workaround is specific to AMD chipset with a PCIe upstream device with device id 0x5aXX Signed-off-by: Asai Thambi S P <asamymuth...@micron.com> Signed-off-by: Sam Bradshaw <sbrads...@micron.com> --- drivers/block/mtip32xx/mtip32xx.c | 53 +++++++++++++++++++++++++++++++++++++ 1 files changed, 53 insertions(+), 0 deletions(-) diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c index 624e9d9..8c462d3 100644 --- a/drivers/block/mtip32xx/mtip32xx.c +++ b/drivers/block/mtip32xx/mtip32xx.c @@ -4479,6 +4479,57 @@ static DEFINE_HANDLER(5); static DEFINE_HANDLER(6); static DEFINE_HANDLER(7); +static void mtip_disable_link_opts(struct driver_data *dd, struct pci_dev *pdev) +{ + int pos; + unsigned short pcie_dev_ctrl; + + pos = pci_find_capability(pdev, PCI_CAP_ID_EXP); + if (pos) { + pci_read_config_word(pdev, + pos + PCI_EXP_DEVCTL, + &pcie_dev_ctrl); + if (pcie_dev_ctrl & (1 << 11) || + pcie_dev_ctrl & (1 << 4)) { + dev_info(&dd->pdev->dev, + "Disabling ERO/No-Snoop on bridge device %04x:%04x\n", + pdev->vendor, pdev->device); + pcie_dev_ctrl &= ~(PCI_EXP_DEVCTL_NOSNOOP_EN | + PCI_EXP_DEVCTL_RELAX_EN); + pci_write_config_word(pdev, + pos + PCI_EXP_DEVCTL, + pcie_dev_ctrl); + } + } +} + +static void mtip_fix_ero_nosnoop(struct driver_data *dd, struct pci_dev *pdev) +{ + /* + * This workaround is specific to AMD/ATI chipset with a PCI upstream + * device with device id 0x5aXX + */ + if (pdev->bus && pdev->bus->self) { + if (pdev->bus->self->vendor == PCI_VENDOR_ID_ATI && + ((pdev->bus->self->device & 0xff00) == 0x5a00)) { + mtip_disable_link_opts(dd, pdev->bus->self); + } else { + /* Check further up the topology */ + struct pci_dev *parent_dev = pdev->bus->self; + if (parent_dev->bus && + parent_dev->bus->parent && + parent_dev->bus->parent->self && + parent_dev->bus->parent->self->vendor == + PCI_VENDOR_ID_ATI && + (parent_dev->bus->parent->self->device & + 0xff00) == 0x5a00) { + mtip_disable_link_opts(dd, + parent_dev->bus->parent->self); + } + } + } +} + /* * Called for each supported PCI device detected. * @@ -4630,6 +4681,8 @@ static int mtip_pci_probe(struct pci_dev *pdev, goto msi_initialize_err; } + mtip_fix_ero_nosnoop(dd, pdev); + /* Initialize the block layer. */ rv = mtip_block_initialize(dd); if (rv < 0) { -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/