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Commit 0dde1c08 authored by Bjorn Helgaas's avatar Bjorn Helgaas
Browse files

PCI: Don't reassign resources that are already aligned 



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: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 81a5e70e

drivers/pci/pci.c

+19 −21
Original line number Diff line number Diff line
@@ -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;

	 * 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;

}



/*