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

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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: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
This commit is contained in:
Bjorn Helgaas 2009-11-04 10:39:18 -07:00 committed by Jesse Barnes
parent f1db6fde09
commit 03db42adfe
1 changed files with 25 additions and 0 deletions
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25
arch/x86/pci/acpi.c
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@ -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,