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PCI: Add support for DMA alias quirks

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Some devices are broken and use a requester ID other than their physical
devfn.  Add a byte, using an existing gap in the pci_dev structure, to
store an alternate "alias" devfn.  A bit in the dev_flags tells us when
this is valid.  We then add the alias as one more step in the
pci_for_each_dma_alias() iterator.

Tested-by: George Spelvin <linux@horizon.com>
Tested-by: Pat Erley <pat-lkml@erley.org>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Alex Williamson 2014-05-22 17:07:43 -06:00 committed by Bjorn Helgaas
parent 6b121592f8
commit 31c2b8153c
2 changed files with 14 additions and 0 deletions
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11
drivers/pci/search.c
View File

@ -37,6 +37,17 @@ int pci_for_each_dma_alias(struct pci_dev *pdev,
if (ret)
return ret;
/*
* If the device is broken and uses an alias requester ID for
* DMA, iterate over that too.
*/
if (unlikely(pdev->dev_flags & PCI_DEV_FLAGS_DMA_ALIAS_DEVFN)) {
ret = fn(pdev, PCI_DEVID(pdev->bus->number,
pdev->dma_alias_devfn), data);
if (ret)
return ret;
}
for (bus = pdev->bus; !pci_is_root_bus(bus); bus = bus->parent) {
struct pci_dev *tmp;

3
include/linux/pci.h
View File

@ -171,6 +171,8 @@ enum pci_dev_flags {
PCI_DEV_FLAGS_ASSIGNED = (__force pci_dev_flags_t) (1 << 2),
/* Flag for quirk use to store if quirk-specific ACS is enabled */
PCI_DEV_FLAGS_ACS_ENABLED_QUIRK = (__force pci_dev_flags_t) (1 << 3),
/* Flag to indicate the device uses dma_alias_devfn */
PCI_DEV_FLAGS_DMA_ALIAS_DEVFN = (__force pci_dev_flags_t) (1 << 4),
};
enum pci_irq_reroute_variant {
@ -268,6 +270,7 @@ struct pci_dev {
u8 rom_base_reg; /* which config register controls the ROM */
u8 pin; /* which interrupt pin this device uses */
u16 pcie_flags_reg; /* cached PCIe Capabilities Register */
u8 dma_alias_devfn;/* devfn of DMA alias, if any */
struct pci_driver *driver; /* which driver has allocated this device */
u64 dma_mask; /* Mask of the bits of bus address this