device/Kconfig: Reduce PCIe hotplug bus numbers and IO resources

The rationale behind this change is that multiple nested bridges using a
lot of bus numbers and IO resources is not likely to be a common hotplug
setup. When there is a large amount of hotplug ports using 32
subordinate busses results in boot failures (e.g. make qemu). 8K IO
busses for hotplug devices is also excessive in most use cases when only
64K is available in total (again make qemu results in failure to
allocate resources but does boot to payload).

Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Change-Id: I8371958037d479e7d2053f49814735e15461ca6e
Reviewed-on: https://review.coreboot.org/c/coreboot/+/74774
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Lean Sheng Tan <sheng.tan@9elements.com>
diff --git a/src/device/Kconfig b/src/device/Kconfig
index cdd843c..71292e8 100644
--- a/src/device/Kconfig
+++ b/src/device/Kconfig
@@ -703,12 +703,10 @@
 
 config PCIEXP_HOTPLUG_BUSES
 	int "PCI Express Hotplug Buses"
-	default  8 if ECAM_MMCONF_SUPPORT && ECAM_MMCONF_BUS_NUMBER <=  64
-	default 16 if ECAM_MMCONF_SUPPORT && ECAM_MMCONF_BUS_NUMBER <= 128
-	default 32
+	default 8
 	help
 	  This is the number of buses allocated for hotplug PCI express
-	  bridges, for use by hotplugged child devices. The default is 32
+	  bridges, for use by hotplugged child devices. The default is 8
 	  buses.
 
 config PCIEXP_HOTPLUG_MEM
@@ -745,11 +743,11 @@
 
 config PCIEXP_HOTPLUG_IO
 	hex "PCI Express Hotplug I/O Space"
-	default 0x2000
+	default 0x800
 	help
 	  This is the amount of I/O space to allocate to hot-plug PCI
 	  express bridges, for use by hotplugged child devices. The default
-	  is 8 KiB.
+	  is 2 KiB.
 
 endif # PCIEXP_HOTPLUG