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Commit 8113587c authored by Zhao, Yu's avatar Zhao, Yu Committed by Jesse Barnes
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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: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: default avatarYu Zhao <yu.zhao@intel.com>
Signed-off-by: default avatarJesse Barnes <jbarnes@virtuousgeek.org>
parent d2174c3c

drivers/pci/pci.c

+13 −8
Original line number Diff line number Diff line
@@ -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)

	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI);

	if (!pos)

		return;



	pos = pci_find_capability(dev, PCI_CAP_ID_EXP);

	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(dev, pos + PCI_EXP_DEVCAP2, &cap);

	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