pci: Avoid assigning PCI resources that are below 0x1000

commit b7598a43f2b4 ("[PATCH] Avoid assigning PCI resources from
zero address") only moved the bus lower address to 0x1000 if the
given bus start address is zero. The comment said 0x1000 is a
reasonable starting value, hence we'd better apply the same
adjustment when the given bus start address is below 0x1000.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/drivers/pci/pci_auto_common.c b/drivers/pci/pci_auto_common.c
index 1837873..84908e6 100644
--- a/drivers/pci/pci_auto_common.c
+++ b/drivers/pci/pci_auto_common.c
@@ -21,9 +21,10 @@
 	/*
 	 * Avoid allocating PCI resources from address 0 -- this is illegal
 	 * according to PCI 2.1 and moreover, this is known to cause Linux IDE
-	 * drivers to fail. Use a reasonable starting value of 0x1000 instead.
+	 * drivers to fail. Use a reasonable starting value of 0x1000 instead
+	 * if the bus start address is below 0x1000.
 	 */
-	res->bus_lower = res->bus_start ? res->bus_start : 0x1000;
+	res->bus_lower = res->bus_start < 0x1000 ? 0x1000 : res->bus_start;
 }
 
 void pciauto_region_align(struct pci_region *res, pci_size_t size)