Re: [PATCH] ACPI: Recode the acpi_get_pci_rootbridge_handle() to boot faster

[Len Brown <lenb@kernel.org>]

On Friday 12 January 2007 14:10, Bjorn Helgaas wrote:
> On Wednesday 06 December 2006 10:17, Bjorn Helgaas wrote:
> > Here's a non-line-wrapped version.  Justin sent this yesterday
> > but it didn't make it to the list for some reason, so I'm
> > trying again.
> 
> Ping!  Any reaction to this?  It makes a BIG difference in
> boot time on large system.s


Applied.
thanks for the ping.

-Len

> > Move acpi_get_pci_rootbridge_handle() from glue.c to pci_root.c and get the
> > root bridge acpi handles by searching the &acpi_pci_roots list instead of
> > walking through the ACPI name space.  This significantly reduces boot time
> > on large I/O systems.
> > 
> > Signed-off-by: Justin Chen <justin.chen@hp.com>
> > 
> > diff -Nru a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> > --- a/drivers/acpi/pci_root.c	2006-11-29 13:57:37.000000000 -0800
> > +++ b/drivers/acpi/pci_root.c	2006-12-04 14:41:14.551395167 -0800
> > @@ -116,6 +116,19 @@
> >  
> >  EXPORT_SYMBOL(acpi_pci_unregister_driver);
> >  
> > +acpi_handle acpi_get_pci_rootbridge_handle(unsigned int seg, unsigned int bus)
> > +{
> > +	struct acpi_pci_root *tmp;
> > +	
> > +	list_for_each_entry(tmp, &acpi_pci_roots, node) {
> > +		if ((tmp->id.segment == (u16) seg) && (tmp->id.bus == (u16) bus))
> > +			return tmp->device->handle;
> > +	}
> > +	return NULL;		
> > +}
> > +
> > +EXPORT_SYMBOL_GPL(acpi_get_pci_rootbridge_handle);
> > +
> >  static acpi_status
> >  get_root_bridge_busnr_callback(struct acpi_resource *resource, void *data)
> >  {
> > diff -Nru a/drivers/acpi/glue.c b/drivers/acpi/glue.c
> > --- a/drivers/acpi/glue.c	2006-12-04 14:42:53.067995523 -0800
> > +++ b/drivers/acpi/glue.c	2006-12-04 14:44:42.723267617 -0800
> > @@ -86,125 +86,6 @@
> >  	return ret;
> >  }
> >  
> > -/* Get PCI root bridge's handle from its segment and bus number */
> > -struct acpi_find_pci_root {
> > -	unsigned int seg;
> > -	unsigned int bus;
> > -	acpi_handle handle;
> > -};
> > -
> > -static acpi_status
> > -do_root_bridge_busnr_callback(struct acpi_resource *resource, void *data)
> > -{
> > -	unsigned long *busnr = (unsigned long *)data;
> > -	struct acpi_resource_address64 address;
> > -
> > -	if (resource->type != ACPI_RESOURCE_TYPE_ADDRESS16 &&
> > -	    resource->type != ACPI_RESOURCE_TYPE_ADDRESS32 &&
> > -	    resource->type != ACPI_RESOURCE_TYPE_ADDRESS64)
> > -		return AE_OK;
> > -
> > -	acpi_resource_to_address64(resource, &address);
> > -	if ((address.address_length > 0) &&
> > -	    (address.resource_type == ACPI_BUS_NUMBER_RANGE))
> > -		*busnr = address.minimum;
> > -
> > -	return AE_OK;
> > -}
> > -
> > -static int get_root_bridge_busnr(acpi_handle handle)
> > -{
> > -	acpi_status status;
> > -	unsigned long bus, bbn;
> > -	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> > -
> > -	acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
> > -
> > -	status = acpi_evaluate_integer(handle, METHOD_NAME__BBN, NULL,
> > -				       &bbn);
> > -	if (status == AE_NOT_FOUND) {
> > -		/* Assume bus = 0 */
> > -		printk(KERN_INFO PREFIX
> > -		       "Assume root bridge [%s] bus is 0\n",
> > -		       (char *)buffer.pointer);
> > -		status = AE_OK;
> > -		bbn = 0;
> > -	}
> > -	if (ACPI_FAILURE(status)) {
> > -		bbn = -ENODEV;
> > -		goto exit;
> > -	}
> > -	if (bbn > 0)
> > -		goto exit;
> > -
> > -	/* _BBN in some systems return 0 for all root bridges */
> > -	bus = -1;
> > -	status = acpi_walk_resources(handle, METHOD_NAME__CRS,
> > -				     do_root_bridge_busnr_callback, &bus);
> > -	/* If _CRS failed, we just use _BBN */
> > -	if (ACPI_FAILURE(status) || (bus == -1))
> > -		goto exit;
> > -	/* We select _CRS */
> > -	if (bbn != bus) {
> > -		printk(KERN_INFO PREFIX
> > -		       "_BBN and _CRS returns different value for %s. Select _CRS\n",
> > -		       (char *)buffer.pointer);
> > -		bbn = bus;
> > -	}
> > -      exit:
> > -	kfree(buffer.pointer);
> > -	return (int)bbn;
> > -}
> > -
> > -static acpi_status
> > -find_pci_rootbridge(acpi_handle handle, u32 lvl, void *context, void **rv)
> > -{
> > -	struct acpi_find_pci_root *find = (struct acpi_find_pci_root *)context;
> > -	unsigned long seg, bus;
> > -	acpi_status status;
> > -	int tmp;
> > -	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> > -
> > -	acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
> > -
> > -	status = acpi_evaluate_integer(handle, METHOD_NAME__SEG, NULL, &seg);
> > -	if (status == AE_NOT_FOUND) {
> > -		/* Assume seg = 0 */
> > -		status = AE_OK;
> > -		seg = 0;
> > -	}
> > -	if (ACPI_FAILURE(status)) {
> > -		status = AE_CTRL_DEPTH;
> > -		goto exit;
> > -	}
> > -
> > -	tmp = get_root_bridge_busnr(handle);
> > -	if (tmp < 0) {
> > -		printk(KERN_ERR PREFIX
> > -		       "Find root bridge failed for %s\n",
> > -		       (char *)buffer.pointer);
> > -		status = AE_CTRL_DEPTH;
> > -		goto exit;
> > -	}
> > -	bus = tmp;
> > -
> > -	if (seg == find->seg && bus == find->bus)
> > -		find->handle = handle;
> > -	status = AE_OK;
> > -      exit:
> > -	kfree(buffer.pointer);
> > -	return status;
> > -}
> > -
> > -acpi_handle acpi_get_pci_rootbridge_handle(unsigned int seg, unsigned int bus)
> > -{
> > -	struct acpi_find_pci_root find = { seg, bus, NULL };
> > -
> > -	acpi_get_devices(PCI_ROOT_HID_STRING, find_pci_rootbridge, &find, NULL);
> > -	return find.handle;
> > -}
> > -EXPORT_SYMBOL_GPL(acpi_get_pci_rootbridge_handle);
> > -
> >  /* Get device's handler per its address under its parent */
> >  struct acpi_find_child {
> >  	acpi_handle handle;
> > 
> > -
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