[V4,08/29] x86/pci: Defer IRQ assignment to device enable time
diff mbox

Message ID 1445576642-29624-9-git-send-email-matt@masarand.com
State New, archived
Headers show

Commit Message

matt@masarand.com Oct. 23, 2015, 5:03 a.m. UTC
The x86 architecture boot code currently traverses the PCI buses with
an extra pass in order to initialise the PCI device IRQs at boot, this
patch avoids this pass and defers the IRQ assignment untill device
enable time which also has the benefit that hot-plugged devices are
assigned IRQs without additional code.

Signed-off-by: Matthew Minter <matt@masarand.com>
---
 arch/x86/include/asm/pci_x86.h |  7 +++--
 arch/x86/kernel/x86_init.c     |  1 -
 arch/x86/pci/irq.c             | 70 +++++++++++++++++++++---------------------
 3 files changed, 39 insertions(+), 39 deletions(-)

Comments

Bjorn Helgaas Dec. 23, 2015, 11:04 p.m. UTC | #1
[+cc Thomas]

Hi Matthew,

On Fri, Oct 23, 2015 at 06:03:41AM +0100, Matthew Minter wrote:
> The x86 architecture boot code currently traverses the PCI buses with
> an extra pass in order to initialise the PCI device IRQs at boot, this
> patch avoids this pass and defers the IRQ assignment untill device
> enable time which also has the benefit that hot-plugged devices are
> assigned IRQs without additional code.

I think the outline of this patch (doing the IRQ init at device
enable-time instead of at boot-time) is good, but I am concerned about
two things:

1) pcibios_lookup_irq() contains a for_each_pci_dev() loop that
updates dev->irq for all devices with the same pirq value.  Previously
we ran that loop at boot-time via this path:

  pci_subsys_init                   # subsys_initcall
    x86_init.pci.init_irq           # .init_irq = x86_default_pci_init_irq
    x86_default_pci_init_irq        # x86_default_pci_init_irq = pcibios_irq_init
    pcibios_irq_init
      x86_init.pci.fixup_irqs       # .fixup_irqs = x86_default_pci_fixup_irqs
      x86_default_pci_fixup_irqs    # x86_default_pci_fixup_irqs = pcibios_fixup_irqs
      pcibios_fixup_irqs
        for_each_pci_dev
          pcibios_lookup_irq

Now we'll run it later, in this path:

  pci_enable_device
    pci_enable_device_flags
      do_pci_enable_device
        pci_assign_irq
          pci_map_irq                   # bridge->map_irq
            pcibios_fixup_irq
              pcibios_lookup_irq
                for_each_pci_dev(dev2)
                  dev2->irq = irq       # <-- potential problem

The problem is that dev2 is an unrelated device and may already have a
driver bound to it, and we shouldn't change dev->irq after a driver
binds to a device.

I don't know enough about interrupts and PIRQ to know whether this is
really a problem in practice or not.  I added Thomas in case he knows.

2) I'm also worried about the fact that we don't do the IRQ init until
a driver calls pci_enable_device().  We've been doing some IRQ init in
pcibios_alloc_irq() in this path for a long time:

  pci_subsys_init
    ...
      pcibios_fixup_irqs                # <-- moved from here ...
        for_each_pci_dev
  ...
  pci_device_probe
    pcibios_alloc_irq
      pcibios_enable_irq                # pcibios_enable_irq = acpi_pci_irq_enable
                                        # (or pirq_enable_irq, x86_of_pci_irq_enable, lguest_enable_irq, etc)
      acpi_pci_irq_enable
    __pci_device_probe
      ...
	pci_drv->probe                  # driver .probe routine
	  ...
	    pci_enable_device
              ...
                pci_fixup_irq           # <-- ... to here

I think there are two problems here:

2.1) We changed the order of pcibios_enable_irq() and pci_fixup_irq().
Both update dev->irq, and I doubt it's safe to reverse the order.

2.2) It's conceivable that a driver may use interrupts without ever
calling pci_enable_device().  That driver would be broken by this
change.

I think we could probably fix both of these worries by calling
pci_assign_irq() from pci_device_probe() instead of from
do_pci_enable_device().

I'm not so sure about the pcibios_lookup_irq() problem.  That's a
little farther outside my area, so I'll have to look at that some
more.

I really want to merge this stuff because it's a major cleanup, so I'm
going to push on this more myself.  I'm just writing this as a
heads-up in case anybody else has ideas.

Bjorn

> Signed-off-by: Matthew Minter <matt@masarand.com>
> ---
>  arch/x86/include/asm/pci_x86.h |  7 +++--
>  arch/x86/kernel/x86_init.c     |  1 -
>  arch/x86/pci/irq.c             | 70 +++++++++++++++++++++---------------------
>  3 files changed, 39 insertions(+), 39 deletions(-)
> 
> diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h
> index fa1195d..16fd8e9 100644
> --- a/arch/x86/include/asm/pci_x86.h
> +++ b/arch/x86/include/asm/pci_x86.h
> @@ -90,6 +90,7 @@ extern unsigned int pcibios_irq_mask;
>  
>  extern raw_spinlock_t pci_config_lock;
>  
> +extern int pci_map_irq(struct pci_dev *dev, u8 slot, u8 pin);
>  extern int (*pcibios_enable_irq)(struct pci_dev *dev);
>  extern void (*pcibios_disable_irq)(struct pci_dev *dev);
>  
> @@ -119,7 +120,7 @@ extern int __init pci_acpi_init(void);
>  extern void __init pcibios_irq_init(void);
>  extern int __init pcibios_init(void);
>  extern int pci_legacy_init(void);
> -extern void pcibios_fixup_irqs(void);
> +extern int pcibios_fixup_irq(struct pci_dev *dev, u8 pin);
>  
>  /* pci-mmconfig.c */
>  
> @@ -200,9 +201,9 @@ static inline void mmio_config_writel(void __iomem *pos, u32 val)
>  #  define x86_default_pci_init		pci_legacy_init
>  # endif
>  # define x86_default_pci_init_irq	pcibios_irq_init
> -# define x86_default_pci_fixup_irqs	pcibios_fixup_irqs
> +# define x86_default_pci_fixup_irq	pcibios_fixup_irq
>  #else
>  # define x86_default_pci_init		NULL
>  # define x86_default_pci_init_irq	NULL
> -# define x86_default_pci_fixup_irqs	NULL
> +# define x86_default_pci_fixup_irq	NULL
>  #endif
> diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
> index 3839628..810f1dd 100644
> --- a/arch/x86/kernel/x86_init.c
> +++ b/arch/x86/kernel/x86_init.c
> @@ -80,7 +80,6 @@ struct x86_init_ops x86_init __initdata = {
>  	.pci = {
>  		.init			= x86_default_pci_init,
>  		.init_irq		= x86_default_pci_init_irq,
> -		.fixup_irqs		= x86_default_pci_fixup_irqs,
>  	},
>  };
>  
> diff --git a/arch/x86/pci/irq.c b/arch/x86/pci/irq.c
> index 350e785..15c507b 100644
> --- a/arch/x86/pci/irq.c
> +++ b/arch/x86/pci/irq.c
> @@ -1021,47 +1021,38 @@ static int pcibios_lookup_irq(struct pci_dev *dev, int assign)
>  	return 1;
>  }
>  
> -void __init pcibios_fixup_irqs(void)
> +int pcibios_fixup_irq(struct pci_dev *dev, u8 pin)
>  {
> -	struct pci_dev *dev = NULL;
> -	u8 pin;
> -
> +	int irq = dev->irq;
>  	DBG(KERN_DEBUG "PCI: IRQ fixup\n");
> -	for_each_pci_dev(dev) {
> -		/*
> -		 * If the BIOS has set an out of range IRQ number, just
> -		 * ignore it.  Also keep track of which IRQ's are
> -		 * already in use.
> -		 */
> -		if (dev->irq >= 16) {
> -			dev_dbg(&dev->dev, "ignoring bogus IRQ %d\n", dev->irq);
> -			dev->irq = 0;
> -		}
> -		/*
> -		 * If the IRQ is already assigned to a PCI device,
> -		 * ignore its ISA use penalty
> -		 */
> -		if (pirq_penalty[dev->irq] >= 100 &&
> -				pirq_penalty[dev->irq] < 100000)
> -			pirq_penalty[dev->irq] = 0;
> -		pirq_penalty[dev->irq]++;
> +	/*
> +	 * If the BIOS has set an out of range IRQ number, just
> +	 * ignore it.  Also keep track of which IRQ's are
> +	 * already in use.
> +	 */
> +	if (irq >= 16) {
> +		dev_dbg(&dev->dev, "ignoring bogus IRQ %d\n", irq);
> +		irq = 0;
>  	}
> +	/*
> +	 * If the IRQ is already assigned to a PCI device,
> +	 * ignore its ISA use penalty
> +	 */
> +	if (pirq_penalty[irq] >= 100 &&
> +			pirq_penalty[irq] < 100000)
> +		pirq_penalty[irq] = 0;
> +	pirq_penalty[irq]++;
>  
> -	if (io_apic_assign_pci_irqs)
> -		return;
> +	if (io_apic_assign_pci_irqs || !pin)
> +		return irq;
>  
> -	dev = NULL;
> -	for_each_pci_dev(dev) {
> -		pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
> -		if (!pin)
> -			continue;
> +	/*
> +	 * Still no IRQ? Try to lookup one...
> +	 */
> +	if (!irq && pcibios_lookup_irq(dev, 0))
> +		irq = dev->irq;
>  
> -		/*
> -		 * Still no IRQ? Try to lookup one...
> -		 */
> -		if (!dev->irq)
> -			pcibios_lookup_irq(dev, 0);
> -	}
> +	return irq;
>  }
>  
>  /*
> @@ -1174,6 +1165,7 @@ int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
>  		struct pci_sysdata *sd = bridge->bus->sysdata;
>  		ACPI_COMPANION_SET(&bridge->dev, sd->companion);
>  	}
> +	bridge->map_irq = pci_map_irq;
>  	return 0;
>  }
>  
> @@ -1201,6 +1193,14 @@ void pcibios_penalize_isa_irq(int irq, int active)
>  		pirq_penalize_isa_irq(irq, active);
>  }
>  
> +int pci_map_irq(struct pci_dev *dev, u8 slot, u8 pin)
> +{
> +	dev->irq = pcibios_fixup_irq(dev, pin);
> +	if (pcibios_enable_irq(dev))
> +		return -1;
> +	return dev->irq;
> +}
> +
>  static int pirq_enable_irq(struct pci_dev *dev)
>  {
>  	u8 pin = 0;
> -- 
> 2.6.2
> 
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Lorenzo Pieralisi Jan. 12, 2016, 11:25 a.m. UTC | #2
Hi Bjorn,

On Wed, Dec 23, 2015 at 05:04:33PM -0600, Bjorn Helgaas wrote:
> [+cc Thomas]
> 
> Hi Matthew,
> 
> On Fri, Oct 23, 2015 at 06:03:41AM +0100, Matthew Minter wrote:
> > The x86 architecture boot code currently traverses the PCI buses with
> > an extra pass in order to initialise the PCI device IRQs at boot, this
> > patch avoids this pass and defers the IRQ assignment untill device
> > enable time which also has the benefit that hot-plugged devices are
> > assigned IRQs without additional code.
> 
> I think the outline of this patch (doing the IRQ init at device
> enable-time instead of at boot-time) is good, but I am concerned about
> two things:
> 
> 1) pcibios_lookup_irq() contains a for_each_pci_dev() loop that
> updates dev->irq for all devices with the same pirq value.  Previously
> we ran that loop at boot-time via this path:
> 
>   pci_subsys_init                   # subsys_initcall
>     x86_init.pci.init_irq           # .init_irq = x86_default_pci_init_irq
>     x86_default_pci_init_irq        # x86_default_pci_init_irq = pcibios_irq_init
>     pcibios_irq_init
>       x86_init.pci.fixup_irqs       # .fixup_irqs = x86_default_pci_fixup_irqs
>       x86_default_pci_fixup_irqs    # x86_default_pci_fixup_irqs = pcibios_fixup_irqs
>       pcibios_fixup_irqs
>         for_each_pci_dev
>           pcibios_lookup_irq
> 
> Now we'll run it later, in this path:
> 
>   pci_enable_device
>     pci_enable_device_flags
>       do_pci_enable_device
>         pci_assign_irq
>           pci_map_irq                   # bridge->map_irq
>             pcibios_fixup_irq
>               pcibios_lookup_irq
>                 for_each_pci_dev(dev2)
>                   dev2->irq = irq       # <-- potential problem
> 
> The problem is that dev2 is an unrelated device and may already have a
> driver bound to it, and we shouldn't change dev->irq after a driver
> binds to a device.

Yes, this looks wrong. On the other hand, removing pci_fixup_irqs from
generic PCI code does not mean that we cannot implement it in x86 using
pci_assign_irq() (in arch code) and leave the current behaviour unchanged.

True, do_pci_enable_device() (or better pci_device_probe() as you say
below) would carry out the fixup unconditionally, but if arch code
carries out the fixup before do_pci_enable_device() I *guess* that the
one carried out in do_pci_enable_device() would become a nop (the fixup
already assigned an IRQ so basically doing it again in do_pci_enable_device()
should not change anything. Still, I am not a fan of this solution either).

I would avoid holding this patch series back, it is a nice clean-up.

> I don't know enough about interrupts and PIRQ to know whether this is
> really a problem in practice or not.  I added Thomas in case he knows.
> 
> 2) I'm also worried about the fact that we don't do the IRQ init until
> a driver calls pci_enable_device().  We've been doing some IRQ init in
> pcibios_alloc_irq() in this path for a long time:
> 
>   pci_subsys_init
>     ...
>       pcibios_fixup_irqs                # <-- moved from here ...
>         for_each_pci_dev
>   ...
>   pci_device_probe
>     pcibios_alloc_irq
>       pcibios_enable_irq                # pcibios_enable_irq = acpi_pci_irq_enable
>                                         # (or pirq_enable_irq, x86_of_pci_irq_enable, lguest_enable_irq, etc)
>       acpi_pci_irq_enable
>     __pci_device_probe
>       ...
> 	pci_drv->probe                  # driver .probe routine
> 	  ...
> 	    pci_enable_device
>               ...
>                 pci_fixup_irq           # <-- ... to here
> 
> I think there are two problems here:
> 
> 2.1) We changed the order of pcibios_enable_irq() and pci_fixup_irq().
> Both update dev->irq, and I doubt it's safe to reverse the order.
> 
> 2.2) It's conceivable that a driver may use interrupts without ever
> calling pci_enable_device().  That driver would be broken by this
> change.
> 
> I think we could probably fix both of these worries by calling
> pci_assign_irq() from pci_device_probe() instead of from
> do_pci_enable_device().

Yes, I think your proposal makes sense (we can even add it to
pci_device_add() (?), the pointers in the bridge used to carry out the
mapping, set-up in pci_create_root_bus()->pcibios_root_bridge_prepare()
are already set-up by the time that function is called).

Actually, executing pci_assign_irq() in pci_device_add(), would not
it solve the issue above too ? Certainly we would still have an issue
with hot-added devices (I have no idea how this works at present
on x86).

We have to decide if the assignment can be done in generic code or
in pcibios_* arches callbacks (to do it on a per-arch basis).

> I'm not so sure about the pcibios_lookup_irq() problem.  That's a
> little farther outside my area, so I'll have to look at that some
> more.
> 
> I really want to merge this stuff because it's a major cleanup, so I'm
> going to push on this more myself.  I'm just writing this as a
> heads-up in case anybody else has ideas.

+1, I am reviewing the ARM/ARM64 code to check for correctness.

Thanks,
Lorenzo

> 
> Bjorn
> 
> > Signed-off-by: Matthew Minter <matt@masarand.com>
> > ---
> >  arch/x86/include/asm/pci_x86.h |  7 +++--
> >  arch/x86/kernel/x86_init.c     |  1 -
> >  arch/x86/pci/irq.c             | 70 +++++++++++++++++++++---------------------
> >  3 files changed, 39 insertions(+), 39 deletions(-)
> > 
> > diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h
> > index fa1195d..16fd8e9 100644
> > --- a/arch/x86/include/asm/pci_x86.h
> > +++ b/arch/x86/include/asm/pci_x86.h
> > @@ -90,6 +90,7 @@ extern unsigned int pcibios_irq_mask;
> >  
> >  extern raw_spinlock_t pci_config_lock;
> >  
> > +extern int pci_map_irq(struct pci_dev *dev, u8 slot, u8 pin);
> >  extern int (*pcibios_enable_irq)(struct pci_dev *dev);
> >  extern void (*pcibios_disable_irq)(struct pci_dev *dev);
> >  
> > @@ -119,7 +120,7 @@ extern int __init pci_acpi_init(void);
> >  extern void __init pcibios_irq_init(void);
> >  extern int __init pcibios_init(void);
> >  extern int pci_legacy_init(void);
> > -extern void pcibios_fixup_irqs(void);
> > +extern int pcibios_fixup_irq(struct pci_dev *dev, u8 pin);
> >  
> >  /* pci-mmconfig.c */
> >  
> > @@ -200,9 +201,9 @@ static inline void mmio_config_writel(void __iomem *pos, u32 val)
> >  #  define x86_default_pci_init		pci_legacy_init
> >  # endif
> >  # define x86_default_pci_init_irq	pcibios_irq_init
> > -# define x86_default_pci_fixup_irqs	pcibios_fixup_irqs
> > +# define x86_default_pci_fixup_irq	pcibios_fixup_irq
> >  #else
> >  # define x86_default_pci_init		NULL
> >  # define x86_default_pci_init_irq	NULL
> > -# define x86_default_pci_fixup_irqs	NULL
> > +# define x86_default_pci_fixup_irq	NULL
> >  #endif
> > diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
> > index 3839628..810f1dd 100644
> > --- a/arch/x86/kernel/x86_init.c
> > +++ b/arch/x86/kernel/x86_init.c
> > @@ -80,7 +80,6 @@ struct x86_init_ops x86_init __initdata = {
> >  	.pci = {
> >  		.init			= x86_default_pci_init,
> >  		.init_irq		= x86_default_pci_init_irq,
> > -		.fixup_irqs		= x86_default_pci_fixup_irqs,
> >  	},
> >  };
> >  
> > diff --git a/arch/x86/pci/irq.c b/arch/x86/pci/irq.c
> > index 350e785..15c507b 100644
> > --- a/arch/x86/pci/irq.c
> > +++ b/arch/x86/pci/irq.c
> > @@ -1021,47 +1021,38 @@ static int pcibios_lookup_irq(struct pci_dev *dev, int assign)
> >  	return 1;
> >  }
> >  
> > -void __init pcibios_fixup_irqs(void)
> > +int pcibios_fixup_irq(struct pci_dev *dev, u8 pin)
> >  {
> > -	struct pci_dev *dev = NULL;
> > -	u8 pin;
> > -
> > +	int irq = dev->irq;
> >  	DBG(KERN_DEBUG "PCI: IRQ fixup\n");
> > -	for_each_pci_dev(dev) {
> > -		/*
> > -		 * If the BIOS has set an out of range IRQ number, just
> > -		 * ignore it.  Also keep track of which IRQ's are
> > -		 * already in use.
> > -		 */
> > -		if (dev->irq >= 16) {
> > -			dev_dbg(&dev->dev, "ignoring bogus IRQ %d\n", dev->irq);
> > -			dev->irq = 0;
> > -		}
> > -		/*
> > -		 * If the IRQ is already assigned to a PCI device,
> > -		 * ignore its ISA use penalty
> > -		 */
> > -		if (pirq_penalty[dev->irq] >= 100 &&
> > -				pirq_penalty[dev->irq] < 100000)
> > -			pirq_penalty[dev->irq] = 0;
> > -		pirq_penalty[dev->irq]++;
> > +	/*
> > +	 * If the BIOS has set an out of range IRQ number, just
> > +	 * ignore it.  Also keep track of which IRQ's are
> > +	 * already in use.
> > +	 */
> > +	if (irq >= 16) {
> > +		dev_dbg(&dev->dev, "ignoring bogus IRQ %d\n", irq);
> > +		irq = 0;
> >  	}
> > +	/*
> > +	 * If the IRQ is already assigned to a PCI device,
> > +	 * ignore its ISA use penalty
> > +	 */
> > +	if (pirq_penalty[irq] >= 100 &&
> > +			pirq_penalty[irq] < 100000)
> > +		pirq_penalty[irq] = 0;
> > +	pirq_penalty[irq]++;
> >  
> > -	if (io_apic_assign_pci_irqs)
> > -		return;
> > +	if (io_apic_assign_pci_irqs || !pin)
> > +		return irq;
> >  
> > -	dev = NULL;
> > -	for_each_pci_dev(dev) {
> > -		pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
> > -		if (!pin)
> > -			continue;
> > +	/*
> > +	 * Still no IRQ? Try to lookup one...
> > +	 */
> > +	if (!irq && pcibios_lookup_irq(dev, 0))
> > +		irq = dev->irq;
> >  
> > -		/*
> > -		 * Still no IRQ? Try to lookup one...
> > -		 */
> > -		if (!dev->irq)
> > -			pcibios_lookup_irq(dev, 0);
> > -	}
> > +	return irq;
> >  }
> >  
> >  /*
> > @@ -1174,6 +1165,7 @@ int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
> >  		struct pci_sysdata *sd = bridge->bus->sysdata;
> >  		ACPI_COMPANION_SET(&bridge->dev, sd->companion);
> >  	}
> > +	bridge->map_irq = pci_map_irq;
> >  	return 0;
> >  }
> >  
> > @@ -1201,6 +1193,14 @@ void pcibios_penalize_isa_irq(int irq, int active)
> >  		pirq_penalize_isa_irq(irq, active);
> >  }
> >  
> > +int pci_map_irq(struct pci_dev *dev, u8 slot, u8 pin)
> > +{
> > +	dev->irq = pcibios_fixup_irq(dev, pin);
> > +	if (pcibios_enable_irq(dev))
> > +		return -1;
> > +	return dev->irq;
> > +}
> > +
> >  static int pirq_enable_irq(struct pci_dev *dev)
> >  {
> >  	u8 pin = 0;
> > -- 
> > 2.6.2
> > 
> > --
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> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
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Patch
diff mbox

diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h
index fa1195d..16fd8e9 100644
--- a/arch/x86/include/asm/pci_x86.h
+++ b/arch/x86/include/asm/pci_x86.h
@@ -90,6 +90,7 @@  extern unsigned int pcibios_irq_mask;
 
 extern raw_spinlock_t pci_config_lock;
 
+extern int pci_map_irq(struct pci_dev *dev, u8 slot, u8 pin);
 extern int (*pcibios_enable_irq)(struct pci_dev *dev);
 extern void (*pcibios_disable_irq)(struct pci_dev *dev);
 
@@ -119,7 +120,7 @@  extern int __init pci_acpi_init(void);
 extern void __init pcibios_irq_init(void);
 extern int __init pcibios_init(void);
 extern int pci_legacy_init(void);
-extern void pcibios_fixup_irqs(void);
+extern int pcibios_fixup_irq(struct pci_dev *dev, u8 pin);
 
 /* pci-mmconfig.c */
 
@@ -200,9 +201,9 @@  static inline void mmio_config_writel(void __iomem *pos, u32 val)
 #  define x86_default_pci_init		pci_legacy_init
 # endif
 # define x86_default_pci_init_irq	pcibios_irq_init
-# define x86_default_pci_fixup_irqs	pcibios_fixup_irqs
+# define x86_default_pci_fixup_irq	pcibios_fixup_irq
 #else
 # define x86_default_pci_init		NULL
 # define x86_default_pci_init_irq	NULL
-# define x86_default_pci_fixup_irqs	NULL
+# define x86_default_pci_fixup_irq	NULL
 #endif
diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index 3839628..810f1dd 100644
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -80,7 +80,6 @@  struct x86_init_ops x86_init __initdata = {
 	.pci = {
 		.init			= x86_default_pci_init,
 		.init_irq		= x86_default_pci_init_irq,
-		.fixup_irqs		= x86_default_pci_fixup_irqs,
 	},
 };
 
diff --git a/arch/x86/pci/irq.c b/arch/x86/pci/irq.c
index 350e785..15c507b 100644
--- a/arch/x86/pci/irq.c
+++ b/arch/x86/pci/irq.c
@@ -1021,47 +1021,38 @@  static int pcibios_lookup_irq(struct pci_dev *dev, int assign)
 	return 1;
 }
 
-void __init pcibios_fixup_irqs(void)
+int pcibios_fixup_irq(struct pci_dev *dev, u8 pin)
 {
-	struct pci_dev *dev = NULL;
-	u8 pin;
-
+	int irq = dev->irq;
 	DBG(KERN_DEBUG "PCI: IRQ fixup\n");
-	for_each_pci_dev(dev) {
-		/*
-		 * If the BIOS has set an out of range IRQ number, just
-		 * ignore it.  Also keep track of which IRQ's are
-		 * already in use.
-		 */
-		if (dev->irq >= 16) {
-			dev_dbg(&dev->dev, "ignoring bogus IRQ %d\n", dev->irq);
-			dev->irq = 0;
-		}
-		/*
-		 * If the IRQ is already assigned to a PCI device,
-		 * ignore its ISA use penalty
-		 */
-		if (pirq_penalty[dev->irq] >= 100 &&
-				pirq_penalty[dev->irq] < 100000)
-			pirq_penalty[dev->irq] = 0;
-		pirq_penalty[dev->irq]++;
+	/*
+	 * If the BIOS has set an out of range IRQ number, just
+	 * ignore it.  Also keep track of which IRQ's are
+	 * already in use.
+	 */
+	if (irq >= 16) {
+		dev_dbg(&dev->dev, "ignoring bogus IRQ %d\n", irq);
+		irq = 0;
 	}
+	/*
+	 * If the IRQ is already assigned to a PCI device,
+	 * ignore its ISA use penalty
+	 */
+	if (pirq_penalty[irq] >= 100 &&
+			pirq_penalty[irq] < 100000)
+		pirq_penalty[irq] = 0;
+	pirq_penalty[irq]++;
 
-	if (io_apic_assign_pci_irqs)
-		return;
+	if (io_apic_assign_pci_irqs || !pin)
+		return irq;
 
-	dev = NULL;
-	for_each_pci_dev(dev) {
-		pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
-		if (!pin)
-			continue;
+	/*
+	 * Still no IRQ? Try to lookup one...
+	 */
+	if (!irq && pcibios_lookup_irq(dev, 0))
+		irq = dev->irq;
 
-		/*
-		 * Still no IRQ? Try to lookup one...
-		 */
-		if (!dev->irq)
-			pcibios_lookup_irq(dev, 0);
-	}
+	return irq;
 }
 
 /*
@@ -1174,6 +1165,7 @@  int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
 		struct pci_sysdata *sd = bridge->bus->sysdata;
 		ACPI_COMPANION_SET(&bridge->dev, sd->companion);
 	}
+	bridge->map_irq = pci_map_irq;
 	return 0;
 }
 
@@ -1201,6 +1193,14 @@  void pcibios_penalize_isa_irq(int irq, int active)
 		pirq_penalize_isa_irq(irq, active);
 }
 
+int pci_map_irq(struct pci_dev *dev, u8 slot, u8 pin)
+{
+	dev->irq = pcibios_fixup_irq(dev, pin);
+	if (pcibios_enable_irq(dev))
+		return -1;
+	return dev->irq;
+}
+
 static int pirq_enable_irq(struct pci_dev *dev)
 {
 	u8 pin = 0;