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>
47 lines
1.4 KiB
C
47 lines
1.4 KiB
C
/*
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driver for LSI L64781 COFDM demodulator
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Copyright (C) 2001 Holger Waechtler for Convergence Integrated Media GmbH
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Marko Kohtala <marko.kohtala@luukku.com>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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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
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef L64781_H
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#define L64781_H
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#include <linux/dvb/frontend.h>
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struct l64781_config
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{
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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_L64781)
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extern struct dvb_frontend* l64781_attach(const struct l64781_config* config,
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struct i2c_adapter* i2c);
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#else
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static inline struct dvb_frontend* l64781_attach(const struct l64781_config* config,
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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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#endif // CONFIG_DVB_L64781
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#endif // L64781_H
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