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PCI: Don't reassign resources that are already aligned

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The "pci=resource_alignment=" kernel argument designates devices for which
we want alignment greater than is required by the PCI specs.  Previously we
set IORESOURCE_UNSET for every MEM resource of those devices, even if the
resource was *already* sufficiently aligned.

If a resource is already sufficiently aligned, leave it alone and don't try
to reassign it.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Bjorn Helgaas 2017-04-17 15:20:58 -05:00
parent 81a5e70e0d
commit 0dde1c08d1
1 changed files with 19 additions and 21 deletions
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40
drivers/pci/pci.c
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@ -5065,30 +5065,28 @@ static void pci_request_resource_alignment(struct pci_dev *dev, int bar,
}
size = resource_size(r);
if (size < align) {
if (size >= align)
return;
/*
* Increase the size of the resource. BARs are aligned on
* their size, so when we reallocate space for this
* resource, we'll allocate it with the larger alignment.
* It also prevents assignment of any other BARs inside the
* size. If we're requesting page alignment, this means no
* other BARs will share the page.
*
* This makes the resource larger than the hardware BAR,
* which may break drivers that compute things based on the
* resource size, e.g., to find registers at a fixed offset
* before the end of the BAR. We hope users don't request
* alignment for such devices.
*/
size = align;
dev_info(&dev->dev, "BAR%d %pR: requesting alignment to %#llx\n",
bar, r, (unsigned long long)align);
/*
* Increase the size of the resource. BARs are aligned on their
* size, so when we reallocate space for this resource, we'll
* allocate it with the larger alignment. It also prevents
* assignment of any other BARs inside the size. If we're
* requesting page alignment, this means no other BARs will share
* the page.
*
* This makes the resource larger than the hardware BAR, which may
* break drivers that compute things based on the resource size,
* e.g., to find registers at a fixed offset before the end of the
* BAR. We hope users don't request alignment for such devices.
*/
dev_info(&dev->dev, "BAR%d %pR: requesting alignment to %#llx\n",
bar, r, (unsigned long long)align);
}
r->flags |= IORESOURCE_UNSET;
r->end = size - 1;
r->start = 0;
r->end = align - 1;
r->flags |= IORESOURCE_UNSET;
}
/*