[PATCH] PCI: Fix calculation of bridge window's size

[AceLan Kao]

There are some 0 resource size pci devices, and it leads to the
accumulator fails to maintain the correct value.
It results in a strange issue on my machine that xhci_hcd failed to init.
   [    2.437278] xhci_hcd 0000:05:00.0: init 0000:05:00.0 fail, -16
   [    2.437300] xhci_hcd: probe of 0000:05:00.0 failed with error -16

To fix this, check if the resource size equals to 0, doesn't increase size.

Fixes: c9c75143a596 ("PCI: Fix calculation of bridge window's size and 
alignment")
CC: sta...@vger.kernel.org # 4.14+

Signed-off-by: AceLan Kao <acelan....@canonical.com>
---
 drivers/pci/setup-bus.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 79b1824e83b4..ae05dde8c6e3 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1061,7 +1061,8 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned 
long mask,
                                r->flags = 0;
                                continue;
                        }
-                       size += max(r_size, align);
+                       if (r_size != 0)
+                               size += max(r_size, align);
                        /* Exclude ranges with size > align from
                           calculation of the alignment. */
                        if (r_size <= align)
-- 
2.17.1