[PATCH] s390/net: lcs: fix build errors when FDDI is a loadable module

[Randy Dunlap]

Require FDDI to be built-in if it is used. LCS needs FDDI to be
built-in to build without errors.

Prevents these build errors:
s390-linux-ld: drivers/s390/net/lcs.o: in function `lcs_new_device':
drivers/s390/net/lcs.c:2150: undefined reference to `fddi_type_trans'
s390-linux-ld: drivers/s390/net/lcs.c:2151: undefined reference to `alloc_fddidev'

This FDDI requirement effectively restores the previous condition
before the blamed patch, when #ifdef CONFIG_FDDI was used, without
testing for CONFIG_FDDI_MODULE.

Fixes: 128272336120 ("s390/net: lcs: use IS_ENABLED() for kconfig detection")
Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Link: lore.kernel.org/r/202306202129.pl0AqK8G-lkp@xxxxxxxxx
Suggested-by: Simon Horman <simon.horman@xxxxxxxxxxxx>
Cc: Alexandra Winter <wintera@xxxxxxxxxxxxx>
Cc: Wenjia Zhang <wenjia@xxxxxxxxxxxxx>
Cc: linux-s390@xxxxxxxxxxxxxxx
Cc: netdev@xxxxxxxxxxxxxxx
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Cc: Sven Schnelle <svens@xxxxxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
---
 drivers/s390/net/Kconfig |    2 ++
 1 file changed, 2 insertions(+)

diff -- a/drivers/s390/net/Kconfig b/drivers/s390/net/Kconfig
--- a/drivers/s390/net/Kconfig
+++ b/drivers/s390/net/Kconfig
@@ -6,11 +6,13 @@ config LCS
 	def_tristate m
 	prompt "Lan Channel Station Interface"
 	depends on CCW && NETDEVICES && (ETHERNET || FDDI)
+	depends on FDDI=y || FDDI=n
 	help
 	  Select this option if you want to use LCS networking on IBM System z.
 	  This device driver supports FDDI (IEEE 802.7) and Ethernet.
 	  To compile as a module, choose M. The module name is lcs.
 	  If you do not know what it is, it's safe to choose Y.
+	  If FDDI is used, it must be built-in (=y).
 
 config CTCM
 	def_tristate m