From 9b174527e7b756cda9f5d9e541f87b7fec9cfdf0 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Wed, 18 Feb 2015 14:12:42 -0300 Subject: [media] Add and use IS_REACHABLE macro In the media drivers, the v4l2 core knows about all submodules and calls into them from a common function. However this cannot work if the modules that get called are loadable and the core is built-in. In that case we get drivers/built-in.o: In function `set_type': drivers/media/v4l2-core/tuner-core.c:301: undefined reference to `tea5767_attach' drivers/media/v4l2-core/tuner-core.c:307: undefined reference to `tea5761_attach' drivers/media/v4l2-core/tuner-core.c:349: undefined reference to `tda9887_attach' drivers/media/v4l2-core/tuner-core.c:405: undefined reference to `xc4000_attach' This was working previously, until the IS_ENABLED() macro was used to replace the construct like #if defined(CONFIG_DVB_CX24110) || (defined(CONFIG_DVB_CX24110_MODULE) && defined(MODULE)) with the difference that the new code no longer checks whether it is being built as a loadable module itself. To fix this, this new patch adds an 'IS_REACHABLE' macro, which evaluates true in exactly the condition that was used previously. The downside of this is that this trades an obvious link error for a more subtle runtime failure, but it is clear that the change that introduced the link error was unintentional and it seems better to revert it for now. Also, a similar change was originally created by Trent Piepho and then reverted by teh change to the IS_ENABLED macro. Ideally Kconfig would be used to avoid the case of a broken dependency, or the code restructured in a way to turn around the dependency, but either way would require much larger changes here. Fixes: 7b34be71db53 ("[media] use IS_ENABLED() macro") See-also: c5dec9fb248e ("V4L/DVB (4751): Fix DBV_FE_CUSTOMISE for card drivers compiled into kernel") Signed-off-by: Arnd Bergmann Signed-off-by: Mauro Carvalho Chehab --- drivers/media/tuners/fc0012.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/media/tuners/fc0012.h') diff --git a/drivers/media/tuners/fc0012.h b/drivers/media/tuners/fc0012.h index 1d08057e3275..9ad32859bab0 100644 --- a/drivers/media/tuners/fc0012.h +++ b/drivers/media/tuners/fc0012.h @@ -49,7 +49,7 @@ struct fc0012_config { bool clock_out; }; -#if IS_ENABLED(CONFIG_MEDIA_TUNER_FC0012) +#if IS_REACHABLE(CONFIG_MEDIA_TUNER_FC0012) extern struct dvb_frontend *fc0012_attach(struct dvb_frontend *fe, struct i2c_adapter *i2c, const struct fc0012_config *cfg); -- cgit v1.2.3