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PCI: Add resource allocation comments

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Add comments in the code to match the allocation strategy of 7c671426dfc3
("PCI: Restrict 64-bit prefetchable bridge windows to 64-bit resources").

No functional change.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Bjorn Helgaas
2014-05-19 18:32:18 -06:00
parent d3689df044
commit 67d29b5c6c
2 changed files with 62 additions and 31 deletions
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58
drivers/pci/setup-bus.c
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@@ -1164,17 +1164,16 @@ void __ref __pci_bus_size_bridges(struct pci_bus *bus,
additional_io_size = pci_hotplug_io_size;
additional_mem_size = pci_hotplug_mem_size;
}
/*
* Follow thru
*/
/* Fall through */
default:
pbus_size_io(bus, realloc_head ? 0 : additional_io_size,
additional_io_size, realloc_head);
/* If the bridge supports prefetchable range, size it
separately. If it doesn't, or its prefetchable window
has already been allocated by arch code, try
non-prefetchable range for both types of PCI memory
resources. */
/*
* If there's a 64-bit prefetchable MMIO window, compute
* the size required to put all 64-bit prefetchable
* resources in it.
*/
b_res = &bus->self->resource[PCI_BRIDGE_RESOURCES];
mask = IORESOURCE_MEM;
prefmask = IORESOURCE_MEM | IORESOURCE_PREFETCH;
@@ -1184,29 +1183,58 @@ void __ref __pci_bus_size_bridges(struct pci_bus *bus,
prefmask, prefmask,
realloc_head ? 0 : additional_mem_size,
additional_mem_size, realloc_head);
/*
* If successful, all non-prefetchable resources
* and any 32-bit prefetchable resources will go in
* the non-prefetchable window.
*/
if (ret == 0) {
/*
* Success, with pref mmio64,
* next will size non-pref or
* non-mmio64 */
mask = prefmask;
type2 = prefmask & ~IORESOURCE_MEM_64;
type3 = prefmask & ~IORESOURCE_PREFETCH;
}
}
/*
* If there is no 64-bit prefetchable window, compute the
* size required to put all prefetchable resources in the
* 32-bit prefetchable window (if there is one).
*/
if (!type2) {
prefmask &= ~IORESOURCE_MEM_64;
ret = pbus_size_mem(bus, prefmask, prefmask,
prefmask, prefmask,
realloc_head ? 0 : additional_mem_size,
additional_mem_size, realloc_head);
if (ret == 0) {
/* Success, next will size non-prefetch. */
/*
* If successful, only non-prefetchable resources
* will go in the non-prefetchable window.
*/
if (ret == 0)
mask = prefmask;
} else
else
additional_mem_size += additional_mem_size;
type2 = type3 = IORESOURCE_MEM;
}
/*
* Compute the size required to put everything else in the
* non-prefetchable window. This includes:
*
* - all non-prefetchable resources
* - 32-bit prefetchable resources if there's a 64-bit
* prefetchable window or no prefetchable window at all
* - 64-bit prefetchable resources if there's no
* prefetchable window at all
*
* Note that the strategy in __pci_assign_resource() must
* match that used here. Specifically, we cannot put a
* 32-bit prefetchable resource in a 64-bit prefetchable
* window.
*/
pbus_size_mem(bus, mask, IORESOURCE_MEM, type2, type3,
realloc_head ? 0 : additional_mem_size,
additional_mem_size, realloc_head);