From: Zhao, Yu Date: Thu, 23 Oct 2008 05:15:39 +0000 (+0800) Subject: PCI: fix ARI code to be compatible with mixed ARI/non-ARI systems X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=8113587c2d14d3be2414190845b2e2617c0aa33b;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git 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 Signed-off-by: Yu Zhao Signed-off-by: Jesse Barnes --- diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 533aeb5fcbe4..21f2ac639cab 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -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