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PCI: fix ARI code to be compatible with mixed ARI/non-ARI systems 

The original ARI support code has a compatibility problem with non-ARI
devices.  If a device doesn't support ARI, turning on ARI forwarding on
its upper level bridge will cause undefined behavior.

This fix turns on ARI forwarding only when the subordinate devices
support it.

Tested-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Yu Zhao <yu.zhao@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
This commit is contained in:
Zhao, Yu 2008-10-23 13:15:39 +08:00 committed by Jesse Barnes
parent d2174c3c07
commit 8113587c2d
1 changed files with 15 additions and 10 deletions
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25
drivers/pci/pci.c
View File

@ -1309,27 +1309,32 @@ void pci_enable_ari(struct pci_dev *dev)
int pos;
u32 cap;
u16 ctrl;
struct pci_dev *bridge;
if (!dev->is_pcie)
if (!dev->is_pcie || dev->devfn)
return;
if (dev->pcie_type != PCI_EXP_TYPE_ROOT_PORT &&
dev->pcie_type != PCI_EXP_TYPE_DOWNSTREAM)
return;
pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI);
if (!pos)
return;
pci_read_config_dword(dev, pos + PCI_EXP_DEVCAP2, &cap);
bridge = dev->bus->self;
if (!bridge || !bridge->is_pcie)
return;
pos = pci_find_capability(bridge, PCI_CAP_ID_EXP);
if (!pos)
return;
pci_read_config_dword(bridge, pos + PCI_EXP_DEVCAP2, &cap);
if (!(cap & PCI_EXP_DEVCAP2_ARI))
return;
pci_read_config_word(dev, pos + PCI_EXP_DEVCTL2, &ctrl);
pci_read_config_word(bridge, pos + PCI_EXP_DEVCTL2, &ctrl);
ctrl |= PCI_EXP_DEVCTL2_ARI;
pci_write_config_word(dev, pos + PCI_EXP_DEVCTL2, ctrl);
pci_write_config_word(bridge, pos + PCI_EXP_DEVCTL2, ctrl);
dev->ari_enabled = 1;
bridge->ari_enabled = 1;
}
int