Commit 81a5e70e authored by Bjorn Helgaas's avatar Bjorn Helgaas
Browse files

PCI: Factor pci_reassigndev_resource_alignment() 



Pull the BAR size adjustment out into a new function,
pci_request_resource_alignment(), and add a comment about how and why we
increase the resource size and alignment.

Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 38274637

drivers/pci/pci.c

+47 −22
Original line number Diff line number Diff line
@@ -5049,6 +5049,48 @@ static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev) 
	return align;

}



static void pci_request_resource_alignment(struct pci_dev *dev, int bar,

					   resource_size_t align)

{

	struct resource *r = &dev->resource[bar];

	resource_size_t size;



	if (!(r->flags & IORESOURCE_MEM))

		return;



	if (r->flags & IORESOURCE_PCI_FIXED) {

		dev_info(&dev->dev, "BAR%d %pR: ignoring requested alignment %#llx\n",

			 bar, r, (unsigned long long)align);

		return;

	}



	size = resource_size(r);

	if (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.

		 */

		size = align;

		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;

}



/*

 * This function disables memory decoding and releases memory resources

 * of the device specified by kernel's boot parameter 'pci=resource_alignment='.
@@ -5060,7 +5102,7 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev) 
{

	int i;

	struct resource *r;

	resource_size_t align, size;

	resource_size_t align;

	u16 command;



	/*
@@ -5090,28 +5132,11 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev) 
	command &= ~PCI_COMMAND_MEMORY;

	pci_write_config_word(dev, PCI_COMMAND, command);



	for (i = 0; i <= PCI_ROM_RESOURCE; i++) {

		r = &dev->resource[i];

		if (!(r->flags & IORESOURCE_MEM))

			continue;

		if (r->flags & IORESOURCE_PCI_FIXED) {

			dev_info(&dev->dev, "Ignoring requested alignment for BAR%d: %pR\n",

				i, r);

			continue;

		}

	for (i = 0; i <= PCI_ROM_RESOURCE; i++)

		pci_request_resource_alignment(dev, i, align);



		size = resource_size(r);

		if (size < align) {

			size = align;

			dev_info(&dev->dev,

				"Rounding up size of resource #%d to %#llx.\n",

				i, (unsigned long long)size);

		}

		r->flags |= IORESOURCE_UNSET;

		r->end = size - 1;

		r->start = 0;

	}

	/* Need to disable bridge's resource window,

	/*

	 * Need to disable bridge's resource window,

	 * to enable the kernel to reassign new resource

	 * window later on.

	 */