[PATCH 3.10 08/46] mtip32xx: Fix ERO and NoSnoop values in PCIe upstream on AMD systems

Greg Kroah-Hartman
2014-07-04T22:39:50Z

From: Asai Thambi S P <asamymuthupa@micron.com>

commit d1e714db8129a1d3670e449b87719c78e2c76f9f upstream.

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 <asamymuthupa@micron.com>
Signed-off-by: Sam Bradshaw <sbradshaw@micron.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/block/mtip32xx/mtip32xx.c | 53 ++++++++++++++++++++++++++++++++++++++
1 file changed, 53 insertions(+)

--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -4284,6 +4284,57 @@ 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.
*
@@ -4435,6 +4486,8 @@ static int mtip_pci_probe(struct pci_dev
goto block_initialize_err;
}

+ mtip_fix_ero_nosnoop(dd, pdev);
+
/* Initialize the block layer. */
rv = mtip_block_initialize(dd);
if (rv < 0) {