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PCI: Disable PCIe Relaxed Ordering if unsupported

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When bit4 is set in the PCIe Device Control register, it indicates
whether the device is permitted to use relaxed ordering.
On some platforms using relaxed ordering can have performance issues or
due to erratum can cause data-corruption. In such cases devices must avoid
using relaxed ordering.

The patch adds a new flag PCI_DEV_FLAGS_NO_RELAXED_ORDERING to indicate that
Relaxed Ordering (RO) attribute should not be used for Transaction Layer
Packets (TLP) targeted towards these affected root complexes.

This patch checks if there is any node in the hierarchy that indicates that
using relaxed ordering is not safe. In such cases the patch turns off the
relaxed ordering by clearing the capability for this device.

Signed-off-by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Acked-by: Ashok Raj <ashok.raj@intel.com>
Acked-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
dingtianhong
2017-08-15 11:23:23 +08:00
committed by David S. Miller
parent 59a361bc6f
commit a99b646afa
3 changed files with 57 additions and 0 deletions
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11
drivers/pci/quirks.c
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@@ -4015,6 +4015,17 @@ DECLARE_PCI_FIXUP_CLASS_EARLY(0x1797, 0x6868, PCI_CLASS_NOT_DEFINED, 8,
DECLARE_PCI_FIXUP_CLASS_EARLY(0x1797, 0x6869, PCI_CLASS_NOT_DEFINED, 8,
quirk_tw686x_class);
/*
* Some devices have problems with Transaction Layer Packets with the Relaxed
* Ordering Attribute set. Such devices should mark themselves and other
* Device Drivers should check before sending TLPs with RO set.
*/
static void quirk_relaxedordering_disable(struct pci_dev *dev)
{
dev->dev_flags |= PCI_DEV_FLAGS_NO_RELAXED_ORDERING;
dev_info(&dev->dev, "Disable Relaxed Ordering Attributes to avoid PCIe Completion erratum\n");
}
/*
* Per PCIe r3.0, sec 2.2.9, "Completion headers must supply the same
* values for the Attribute as were supplied in the header of the