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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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43
drivers/pci/probe.c
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@@ -1762,6 +1762,48 @@ static void pci_configure_extended_tags(struct pci_dev *dev)
PCI_EXP_DEVCTL_EXT_TAG);
}
/**
* pcie_relaxed_ordering_enabled - Probe for PCIe relaxed ordering enable
* @dev: PCI device to query
*
* Returns true if the device has enabled relaxed ordering attribute.
*/
bool pcie_relaxed_ordering_enabled(struct pci_dev *dev)
{
u16 v;
pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &v);
return !!(v & PCI_EXP_DEVCTL_RELAX_EN);
}
EXPORT_SYMBOL(pcie_relaxed_ordering_enabled);
static void pci_configure_relaxed_ordering(struct pci_dev *dev)
{
struct pci_dev *root;
/* PCI_EXP_DEVICE_RELAX_EN is RsvdP in VFs */
if (dev->is_virtfn)
return;
if (!pcie_relaxed_ordering_enabled(dev))
return;
/*
* For now, we only deal with Relaxed Ordering issues with Root
* Ports. Peer-to-Peer DMA is another can of worms.
*/
root = pci_find_pcie_root_port(dev);
if (!root)
return;
if (root->dev_flags & PCI_DEV_FLAGS_NO_RELAXED_ORDERING) {
pcie_capability_clear_word(dev, PCI_EXP_DEVCTL,
PCI_EXP_DEVCTL_RELAX_EN);
dev_info(&dev->dev, "Disable Relaxed Ordering because the Root Port didn't support it\n");
}
}
static void pci_configure_device(struct pci_dev *dev)
{
struct hotplug_params hpp;
@@ -1769,6 +1811,7 @@ static void pci_configure_device(struct pci_dev *dev)
pci_configure_mps(dev);
pci_configure_extended_tags(dev);
pci_configure_relaxed_ordering(dev);
memset(&hpp, 0, sizeof(hpp));
ret = pci_get_hp_params(dev, &hpp);