linux/drivers/media/dvb-frontends/dib3000.h
Arnd Bergmann 9b174527e7 [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: 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>
2015-04-08 15:02:07 -03:00

57 lines
1.7 KiB
C

/*
* public header file of the frontend drivers for mobile DVB-T demodulators
* DiBcom 3000M-B and DiBcom 3000P/M-C (http://www.dibcom.fr/)
*
* Copyright (C) 2004-5 Patrick Boettcher (patrick.boettcher@desy.de)
*
* based on GPL code from DibCom, which has
*
* Copyright (C) 2004 Amaury Demol for DiBcom (ademol@dibcom.fr)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, version 2.
*
* Acknowledgements
*
* Amaury Demol (ademol@dibcom.fr) from DiBcom for providing specs and driver
* sources, on which this driver (and the dvb-dibusb) are based.
*
* see Documentation/dvb/README.dvb-usb for more information
*
*/
#ifndef DIB3000_H
#define DIB3000_H
#include <linux/dvb/frontend.h>
struct dib3000_config
{
/* the demodulator's i2c address */
u8 demod_address;
};
struct dib_fe_xfer_ops
{
/* pid and transfer handling is done in the demodulator */
int (*pid_parse)(struct dvb_frontend *fe, int onoff);
int (*fifo_ctrl)(struct dvb_frontend *fe, int onoff);
int (*pid_ctrl)(struct dvb_frontend *fe, int index, int pid, int onoff);
int (*tuner_pass_ctrl)(struct dvb_frontend *fe, int onoff, u8 pll_ctrl);
};
#if IS_REACHABLE(CONFIG_DVB_DIB3000MB)
extern struct dvb_frontend* dib3000mb_attach(const struct dib3000_config* config,
struct i2c_adapter* i2c, struct dib_fe_xfer_ops *xfer_ops);
#else
static inline struct dvb_frontend* dib3000mb_attach(const struct dib3000_config* config,
struct i2c_adapter* i2c, struct dib_fe_xfer_ops *xfer_ops)
{
printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
return NULL;
}
#endif // CONFIG_DVB_DIB3000MB
#endif // DIB3000_H