forked from Minki/linux
9b174527e7
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:7b34be71db("[media] use IS_ENABLED() macro") See-also:c5dec9fb24("V4L/DVB (4751): Fix DBV_FE_CUSTOMISE for card drivers compiled into kernel") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
48 lines
1.4 KiB
C
48 lines
1.4 KiB
C
/*
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* Sharp s921 driver
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*
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* Copyright (C) 2009 Mauro Carvalho Chehab
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* Copyright (C) 2009 Douglas Landgraf <dougsland@redhat.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation version 2.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#ifndef S921_H
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#define S921_H
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#include <linux/kconfig.h>
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#include <linux/dvb/frontend.h>
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struct s921_config {
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/* the demodulator's i2c address */
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u8 demod_address;
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};
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#if IS_REACHABLE(CONFIG_DVB_S921)
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extern struct dvb_frontend *s921_attach(const struct s921_config *config,
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struct i2c_adapter *i2c);
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extern struct i2c_adapter *s921_get_tuner_i2c_adapter(struct dvb_frontend *);
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#else
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static inline struct dvb_frontend *s921_attach(
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const struct s921_config *config, struct i2c_adapter *i2c)
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{
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printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
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return NULL;
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}
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static struct i2c_adapter *
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s921_get_tuner_i2c_adapter(struct dvb_frontend *fe)
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{
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printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
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return NULL;
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}
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#endif
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#endif /* S921_H */
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