[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>
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 1e74e1e..df49530 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -881,13 +881,6 @@
if (atomic_sub_return(1, &dev->enable_cnt) != 0)
return;
- if (dev->msi_enabled)
- disable_msi_mode(dev, pci_find_capability(dev, PCI_CAP_ID_MSI),
- PCI_CAP_ID_MSI);
- if (dev->msix_enabled)
- disable_msi_mode(dev, pci_find_capability(dev, PCI_CAP_ID_MSI),
- PCI_CAP_ID_MSIX);
-
pci_read_config_word(dev, PCI_COMMAND, &pci_command);
if (pci_command & PCI_COMMAND_MASTER) {
pci_command &= ~PCI_COMMAND_MASTER;
@@ -1277,6 +1270,33 @@
}
}
+/**
+ * pci_msi_off - disables any msi or msix capabilities
+ * @pdev: the PCI device to operate on
+ *
+ * If you want to use msi see pci_enable_msi and friends.
+ * This is a lower level primitive that allows us to disable
+ * msi operation at the device level.
+ */
+void pci_msi_off(struct pci_dev *dev)
+{
+ int pos;
+ u16 control;
+
+ pos = pci_find_capability(dev, PCI_CAP_ID_MSI);
+ if (pos) {
+ pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &control);
+ control &= ~PCI_MSI_FLAGS_ENABLE;
+ pci_write_config_word(dev, pos + PCI_MSI_FLAGS, control);
+ }
+ pos = pci_find_capability(dev, PCI_CAP_ID_MSIX);
+ if (pos) {
+ pci_read_config_word(dev, pos + PCI_MSIX_FLAGS, &control);
+ control &= ~PCI_MSIX_FLAGS_ENABLE;
+ pci_write_config_word(dev, pos + PCI_MSIX_FLAGS, control);
+ }
+}
+
#ifndef HAVE_ARCH_PCI_SET_DMA_MASK
/*
* These can be overridden by arch-specific implementations