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authorBjorn Helgaas <bhelgaas@google.com>2017-09-07 13:24:18 -0500
committerBjorn Helgaas <bhelgaas@google.com>2017-09-07 13:24:18 -0500
commit79ab592c700e969d32770dcd1ae39ac64c328812 (patch)
treea634c54a4ff41dfd53027e97db4edab5de169c88 /drivers/pci
parent33db87de6ab7ba9a3cca5b57033621ad154c1d0a (diff)
parent235b2c776bc3c69016329914a3c085e7084bbaa9 (diff)
Merge branch 'pci/msi' into next
* pci/msi: PCI/MSI: Assume MSIs use real Requester ID, not an alias
Diffstat (limited to 'drivers/pci')
-rw-r--r--drivers/pci/msi.c27
1 files changed, 22 insertions, 5 deletions
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 253d92409bb3..2f0dd02d78b7 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -1458,13 +1458,30 @@ struct irq_domain *pci_msi_create_irq_domain(struct fwnode_handle *fwnode,
}
EXPORT_SYMBOL_GPL(pci_msi_create_irq_domain);
+/*
+ * Users of the generic MSI infrastructure expect a device to have a single ID,
+ * so with DMA aliases we have to pick the least-worst compromise. Devices with
+ * DMA phantom functions tend to still emit MSIs from the real function number,
+ * so we ignore those and only consider topological aliases where either the
+ * alias device or RID appears on a different bus number. We also make the
+ * reasonable assumption that bridges are walked in an upstream direction (so
+ * the last one seen wins), and the much braver assumption that the most likely
+ * case is that of PCI->PCIe so we should always use the alias RID. This echoes
+ * the logic from intel_irq_remapping's set_msi_sid(), which presumably works
+ * well enough in practice; in the face of the horrible PCIe<->PCI-X conditions
+ * for taking ownership all we can really do is close our eyes and hope...
+ */
static int get_msi_id_cb(struct pci_dev *pdev, u16 alias, void *data)
{
u32 *pa = data;
+ u8 bus = PCI_BUS_NUM(*pa);
+
+ if (pdev->bus->number != bus || PCI_BUS_NUM(alias) != bus)
+ *pa = alias;
- *pa = alias;
return 0;
}
+
/**
* pci_msi_domain_get_msi_rid - Get the MSI requester id (RID)
* @domain: The interrupt domain
@@ -1478,7 +1495,7 @@ static int get_msi_id_cb(struct pci_dev *pdev, u16 alias, void *data)
u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev)
{
struct device_node *of_node;
- u32 rid = 0;
+ u32 rid = PCI_DEVID(pdev->bus->number, pdev->devfn);
pci_for_each_dma_alias(pdev, get_msi_id_cb, &rid);
@@ -1494,14 +1511,14 @@ u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev)
* @pdev: The PCI device
*
* Use the firmware data to find a device-specific MSI domain
- * (i.e. not one that is ste as a default).
+ * (i.e. not one that is set as a default).
*
- * Returns: The coresponding MSI domain or NULL if none has been found.
+ * Returns: The corresponding MSI domain or NULL if none has been found.
*/
struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev)
{
struct irq_domain *dom;
- u32 rid = 0;
+ u32 rid = PCI_DEVID(pdev->bus->number, pdev->devfn);
pci_for_each_dma_alias(pdev, get_msi_id_cb, &rid);
dom = of_msi_map_get_device_domain(&pdev->dev, rid);

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