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[PATCH] msi: sanely support hardware level msi disabling

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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 <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Greg KH <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Eric W. Biederman 2007-03-05 00:30:07 -08:00 • committed by Linus Torvalds
commit f5f2b13129
7 changed files with 35 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

2
drivers/pci/msi.c
View file

@ -211,7 +211,7 @@ static void enable_msi_mode(struct pci_dev *dev, int pos, int type)
pci_intx(dev, 0); /* disable intx */
}
void disable_msi_mode(struct pci_dev *dev, int pos, int type)
static void disable_msi_mode(struct pci_dev *dev, int pos, int type)
{
u16 control;

34
drivers/pci/pci.c
View file

@ -881,13 +881,6 @@ pci_disable_device(struct pci_dev *dev)
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_intx(struct pci_dev *pdev, int enable)
}
}
/**
* 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

2
drivers/pci/pci.h
View file

@ -46,10 +46,8 @@ extern struct rw_semaphore pci_bus_sem;
extern unsigned int pci_pm_d3_delay;
#ifdef CONFIG_PCI_MSI
void disable_msi_mode(struct pci_dev *dev, int pos, int type);
void pci_no_msi(void);
#else
static inline void disable_msi_mode(struct pci_dev *dev, int pos, int type) { }
static inline void pci_no_msi(void) { }
#endif

4
drivers/pci/quirks.c
View file

@ -1438,8 +1438,8 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_E7525_MCH, quir
*/
static void __devinit quirk_pcie_pxh(struct pci_dev *dev)
{
disable_msi_mode(dev, pci_find_capability(dev, PCI_CAP_ID_MSI),
PCI_CAP_ID_MSI);
pci_msi_off(dev);
dev->no_msi = 1;
printk(KERN_WARNING "PCI: PXH quirk detected, "