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Commit f5f2b131 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Linus Torvalds
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[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: default avatarEric 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 58a53b24

arch/powerpc/kernel/irq.c

+0 −1
Original line number Diff line number Diff line
@@ -968,7 +968,6 @@ void pci_scan_msi_device(struct pci_dev *dev) {} 
int pci_enable_msix(struct pci_dev* dev, struct msix_entry *entries, int nvec) {return -1;}

void pci_disable_msix(struct pci_dev *dev) {}

void msi_remove_pci_irq_vectors(struct pci_dev *dev) {}

void disable_msi_mode(struct pci_dev *dev, int pos, int type) {}

void pci_no_msi(void) {}

EXPORT_SYMBOL(pci_enable_msix);

EXPORT_SYMBOL(pci_disable_msix);

drivers/pci/msi.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

drivers/pci/pci.c

+27 −7
Original line number Diff line number Diff line
@@ -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

drivers/pci/pci.h

+0 −2
Original line number Diff line number Diff line
@@ -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

drivers/pci/quirks.c

+2 −2
Original line number Diff line number Diff line
@@ -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, "