On Wed, 2012-05-30 at 16:34 +0800, Gavin Shan wrote:
> Hi Alex,
>
> >DMA transactions are tagged with the source ID of the device making
> >the request. Occasionally hardware screws this up and uses the
> >source ID of a different device (often the wrong function number of
> >a multifunction device). A specific Ricoh multifunction device is
> >a prime example of this problem and included in this patch. The
> >purpose of this function is that given a pci_dev, return the pci_dev
> >to use as the source ID for DMA. When hardware works correctly,
> >this returns the input device. For the components of the Ricoh
> >multifunction device, return the pci_dev for function 0.
> >
> >This will be used by IOMMU drivers for determining the boundaries
> >of IOMMU groups as multiple devices using the same source ID must
> >be contained within the same group. This can also be used by
> >existing streaming DMA paths for the same purpose.
> >
> >Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> >---
> >
> > drivers/pci/quirks.c | 40 ++++++++++++++++++++++++++++++++++++++++
> > include/linux/pci.h | 5 +++++
> > 2 files changed, 45 insertions(+)
> >
> >diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> >index 2a75216..004e167 100644
> >--- a/drivers/pci/quirks.c
> >+++ b/drivers/pci/quirks.c
> >@@ -3179,3 +3179,43 @@ int pci_dev_specific_reset(struct pci_dev *dev, int probe)
> >
> > return -ENOTTY;
> > }
> >+
> >+static struct pci_dev *pci_func_0_dma_source(struct pci_dev *dev)
> >+{
> >+ return pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
> >+}
>
> I think we needn't retrieve the PCI device passed in again from the list
> of PCI devices if its function number is zero.
>
> if (!PCI_FUNC(dev->devfn))
> return dev;
I guess I was expecting we wouldn't quirk a function 0 device, but
looking again at the bug below I see that I am including the func 0
vendor/device. I've also got a bad cut-n-paste as I'm including the
same device twice. I'll take your suggestion. Thanks,
Alex
> >+
> >+static const struct pci_dev_dma_source {
> >+ u16 vendor;
> >+ u16 device;
> >+ struct pci_dev *(*dma_source)(struct pci_dev *dev);
> >+} pci_dev_dma_source[] = {
> >+ /*
> >+ * https://bugzilla.redhat.com/show_bug.cgi?id=605888
> >+ *
> >+ * Some Ricoh devices use the function 0 source ID for DMA on
> >+ * other functions of a multifunction device. The DMA devices
> >+ * is therefore function 0, which will have implications of the
> >+ * iommu grouping of these devices.
> >+ */
> >+ { PCI_VENDOR_ID_RICOH, 0xe822, pci_func_0_dma_source },
> >+ { PCI_VENDOR_ID_RICOH, 0xe230, pci_func_0_dma_source },
> >+ { PCI_VENDOR_ID_RICOH, 0xe832, pci_func_0_dma_source },
> >+ { PCI_VENDOR_ID_RICOH, 0xe832, pci_func_0_dma_source },
> >+ { 0 }
> >+};
> >+
> >+struct pci_dev *pci_dma_source(struct pci_dev *dev)
> >+{
> >+ const struct pci_dev_dma_source *i;
> >+
> >+ for (i = pci_dev_dma_source; i->dma_source; i++) {
> >+ if ((i->vendor == dev->vendor ||
> >+ i->vendor == (u16)PCI_ANY_ID) &&
> >+ (i->device == dev->device ||
> >+ i->device == (u16)PCI_ANY_ID))
> >+ return i->dma_source(dev);
> >+ }
> >+
> >+ return dev;
> >+}
> >diff --git a/include/linux/pci.h b/include/linux/pci.h
> >index d8c379d..5bc7502 100644
> >--- a/include/linux/pci.h
> >+++ b/include/linux/pci.h
> >@@ -1486,9 +1486,14 @@ enum pci_fixup_pass {
> >
> > #ifdef CONFIG_PCI_QUIRKS
> > void pci_fixup_device(enum pci_fixup_pass pass, struct pci_dev *dev);
> >+struct pci_dev *pci_dma_source(struct pci_dev *dev);
> > #else
> > static inline void pci_fixup_device(enum pci_fixup_pass pass,
> > struct pci_dev *dev) {}
> >+static inline struct pci_dev *pci_dma_source(struct pci_dev *dev)
> >+{
> >+ return dev;
> >+}
> > #endif
> >
> > void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen);
> >
> >--
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> >
>
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