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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: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Bjorn Helgaas 2017-04-14 14:12:06 -05:00
parent 3827463769
commit 81a5e70e0d
1 changed files with 47 additions and 22 deletions
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69
drivers/pci/pci.c
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@ -5049,6 +5049,48 @@ out:
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.
*/