[PATCH] msi: sanely support hardware level msi disabling

In some cases when we are not using msi we need a way to ensure that the
hardware does not have an msi capability enabled.  Currently the code has been
calling disable_msi_mode to try and achieve that.  However disable_msi_mode
has several other side effects and is only available when msi support is
compiled in so it isn't really appropriate.

Instead this patch implements pci_msi_off which disables all msi and msix
capabilities unconditionally with no additional side effects.

pci_disable_device was redundantly clearing the bus master enable flag and
clearing the msi enable bit.  A device that is not allowed to perform bus
mastering operations cannot generate intx or msi interrupt messages as those
are essentially a special case of dma, and require bus mastering.  So the call
in pci_disable_device to disable msi capabilities was redundant.

quirk_pcie_pxh also called disable_msi_mode and is updated to use pci_msi_off.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 5 insertions, 3 deletions

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 2c4b6842dfb9..78417e421b4c 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -543,6 +543,7 @@ void pci_set_master(struct pci_dev *dev);
 int __must_check pci_set_mwi(struct pci_dev *dev);
 void pci_clear_mwi(struct pci_dev *dev);
 void pci_intx(struct pci_dev *dev, int enable);
+void pci_msi_off(struct pci_dev *dev);
 int pci_set_dma_mask(struct pci_dev *dev, u64 mask);
 int pci_set_consistent_dma_mask(struct pci_dev *dev, u64 mask);
 void pci_update_resource(struct pci_dev *dev, struct resource *res, int resno);
diff --git a/include/linux/pci_regs.h b/include/linux/pci_regs.h
index 7a6d34ee5ab1..f09cce2357ff 100644
--- a/include/linux/pci_regs.h
+++ b/include/linux/pci_regs.h
@@ -292,9 +292,10 @@
 #define PCI_MSI_DATA_64         12      /* 16 bits of data for 64-bit devices */
 #define PCI_MSI_MASK_BIT        16      /* Mask bits register */
 
-/* MSI-X registers (these are at offset PCI_MSI_FLAGS) */
-#define PCI_MSIX_FLAGS_QSIZE    0x7FF
-#define PCI_MSIX_FLAGS_ENABLE   (1 << 15)
+/* MSI-X registers (these are at offset PCI_MSIX_FLAGS) */
+#define PCI_MSIX_FLAGS          2
+#define  PCI_MSIX_FLAGS_QSIZE   0x7FF
+#define  PCI_MSIX_FLAGS_ENABLE  (1 << 15)
 #define PCI_MSIX_FLAGS_BIRMASK  (7 << 0)
 #define PCI_MSIX_FLAGS_BITMASK  (1 << 0)