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Commit 03db42ad authored by Bjorn Helgaas's avatar Bjorn Helgaas Committed by Jesse Barnes
Browse files

x86/PCI: fix bogus host bridge window start/end alignment from _CRS 

PCI device BARs are guaranteed to start and end on at least a four-byte
(I/O) or a sixteen-byte (MMIO) boundary because they're aligned on their
size and the low BAR bits are reserved.  PCI-to-PCI bridge apertures
have even larger alignment restrictions.

However, some BIOSes (e.g., HP DL360 BIOS P31) report host bridge windows
like "[io  0x0000-0x2cfe]".  This is wrong because it excludes the last
port at 0x2cff: it's impossible for a downstream device to claim 0x2cfe
without also claiming 0x2cff.  In fact, this BIOS configures a device
behind the bridge to "[io  0x2c00-0x2cff]", so we know the window actually
does include 0x2cff.

This patch rounds the start and end of apertures to the appropriate
boundary.  I experimentally determined that Windows contains a similar
workaround; details here:

    http://bugzilla.kernel.org/show_bug.cgi?id=14337



Signed-off-by: default avatarBjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: default avatarJesse Barnes <jbarnes@virtuousgeek.org>
parent f1db6fde

arch/x86/pci/acpi.c

+25 −0
Original line number Diff line number Diff line
@@ -59,6 +59,30 @@ bus_has_transparent_bridge(struct pci_bus *bus) 
	return false;

}



static void

align_resource(struct acpi_device *bridge, struct resource *res)

{

	int align = (res->flags & IORESOURCE_MEM) ? 16 : 4;



	/*

	 * Host bridge windows are not BARs, but the decoders on the PCI side

	 * that claim this address space have starting alignment and length

	 * constraints, so fix any obvious BIOS goofs.

	 */

	if (res->start & (align - 1)) {

		dev_printk(KERN_DEBUG, &bridge->dev,

			   "host bridge window %pR invalid; "

			   "aligning start to %d-byte boundary\n", res, align);

		res->start &= ~(align - 1);

	}

	if ((res->end + 1) & (align - 1)) {

		dev_printk(KERN_DEBUG, &bridge->dev,

			   "host bridge window %pR invalid; "

			   "aligning end to %d-byte boundary\n", res, align);

		res->end = roundup(res->end, align) - 1;

	}

}



static acpi_status

setup_resource(struct acpi_resource *acpi_res, void *data)

{
@@ -107,6 +131,7 @@ setup_resource(struct acpi_resource *acpi_res, void *data) 
	res->start = start;

	res->end = end;

	res->child = NULL;

	align_resource(info->bridge, res);



	if (!(pci_probe & PCI_USE__CRS)) {

		dev_printk(KERN_DEBUG, &info->bridge->dev,