In commit 462d9303 ("PCI: Align P2P windows using pcibios_window_alignment()"),
it introduce a new method to calculate the window alignment of P2P bridge.
When the io_window_1k is set, the calculation for the io resource alignment
is different from the original one. In the original logic before 462d9303,
the alignment is no bigger than 4K even the io_window_1k is set. The logic
introduced in 462d9303 will limit the alignment to 1k in this case.
This patch fix this issue.
Here is an example for this case.
Assume:
1. pcibios_window_alignment() return 1.
2. window_alignment() return PCI_P2P_DEFAULT_IO_ALIGN_1K.
3. one of the child device has an IO resource with size of 2K.
Result comparison:
Before 462d9303 After 462d9303
min_align 1k 1k
|
after loop |
V
min_align 2k 2k
|
check boundary |
V
min_align 2k 1k
After applying the change:
Result comparison:
with 462d9303 with this patch
min_align 1k 1k
io_align 1k 4k
|
after loop |
V
min_align 2k 2k
io_align 1k 4k
|
check boundary |
V
min_align 1k 2k
io_align 1k 1k
Signed-off-by: Wei Yang <weiyang@xxxxxxxxxxxxxxxxxx>
---
drivers/pci/setup-bus.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index d4f1ad9..6c111e9 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -755,6 +755,10 @@ static void pbus_size_io(struct pci_bus *bus, resource_size_t min_size,
return;
io_align = min_align = window_alignment(bus, IORESOURCE_IO);
+ /* Don't exceed 4KiB for windows requesting 1KiB alignment */
+ if (bus->self->io_window_1k && io_align == PCI_P2P_DEFAULT_IO_ALIGN_1K)
+ io_align = PCI_P2P_DEFAULT_IO_ALIGN;
+
list_for_each_entry(dev, &bus->devices, bus_list) {
int i;
--
1.7.5.4
--
To unsubscribe from this list: send the line "unsubscribe linux-pci" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
