As reported by Antti and by Stephen:
drivers/built-in.o: In function `sms_ir_event':
/home/david/checkouts/linux/drivers/media/common/siano/smsir.c:48: undefined reference to `ir_raw_event_store'
/home/david/checkouts/linux/drivers/media/common/siano/smsir.c:50: undefined reference to `ir_raw_event_handle'
drivers/built-in.o: In function `sms_ir_init':
/home/david/checkouts/linux/drivers/media/common/siano/smsir.c:56: undefined reference to `smscore_get_board_id'
/home/david/checkouts/linux/drivers/media/common/siano/smsir.c:60: undefined reference to `rc_allocate_device'
/home/david/checkouts/linux/drivers/media/common/siano/smsir.c:72: undefined reference to `sms_get_board'
/home/david/checkouts/linux/drivers/media/common/siano/smsir.c:92: undefined reference to `sms_get_board'
/home/david/checkouts/linux/drivers/media/common/siano/smsir.c:97: undefined reference to `rc_register_device'
/home/david/checkouts/linux/drivers/media/common/siano/smsir.c:100: undefined reference to `rc_free_device'
drivers/built-in.o: In function `sms_ir_exit':
/home/david/checkouts/linux/drivers/media/common/siano/smsir.c:111: undefined reference to `rc_unregister_device'
make: *** [vmlinux] Error 1

Caused by commit fdd1eeb4 "[media] siano: allow compiling it without RC support"
And it happens when CONFIG_SMS_SIANO_RC=y and CONFIG_RC_CORE=m .
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>