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-rw-r--r--drivers/pci/pci.c19
-rw-r--r--drivers/pci/search.c6
2 files changed, 24 insertions, 1 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e87196cc1a7f..ab2b8bcd29bf 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -6033,7 +6033,9 @@ bool pci_devs_are_dma_aliases(struct pci_dev *dev1, struct pci_dev *dev2)
return (dev1->dma_alias_mask &&
test_bit(dev2->devfn, dev1->dma_alias_mask)) ||
(dev2->dma_alias_mask &&
- test_bit(dev1->devfn, dev2->dma_alias_mask));
+ test_bit(dev1->devfn, dev2->dma_alias_mask)) ||
+ pci_real_dma_dev(dev1) == dev2 ||
+ pci_real_dma_dev(dev2) == dev1;
}
bool pci_device_is_present(struct pci_dev *pdev)
@@ -6057,6 +6059,21 @@ void pci_ignore_hotplug(struct pci_dev *dev)
}
EXPORT_SYMBOL_GPL(pci_ignore_hotplug);
+/**
+ * pci_real_dma_dev - Get PCI DMA device for PCI device
+ * @dev: the PCI device that may have a PCI DMA alias
+ *
+ * Permits the platform to provide architecture-specific functionality to
+ * devices needing to alias DMA to another PCI device on another PCI bus. If
+ * the PCI device is on the same bus, it is recommended to use
+ * pci_add_dma_alias(). This is the default implementation. Architecture
+ * implementations can override this.
+ */
+struct pci_dev __weak *pci_real_dma_dev(struct pci_dev *dev)
+{
+ return dev;
+}
+
resource_size_t __weak pcibios_default_alignment(void)
{
return 0;
diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index bade14002fd8..efdb8b56035f 100644
--- a/drivers/pci/search.c
+++ b/drivers/pci/search.c
@@ -32,6 +32,12 @@ int pci_for_each_dma_alias(struct pci_dev *pdev,
struct pci_bus *bus;
int ret;
+ /*
+ * The device may have an explicit alias requester ID for DMA where the
+ * requester is on another PCI bus.
+ */
+ pdev = pci_real_dma_dev(pdev);
+
ret = fn(pdev, pci_dev_id(pdev), data);
if (ret)
return ret;