linux/drivers/media/tuners/fc0011.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

42 lines
955 B
C

#ifndef LINUX_FC0011_H_
#define LINUX_FC0011_H_
#include <linux/kconfig.h>
#include "dvb_frontend.h"
/** struct fc0011_config - fc0011 hardware config
*
* @i2c_address: I2C bus address.
*/
struct fc0011_config {
u8 i2c_address;
};
/** enum fc0011_fe_callback_commands - Frontend callbacks
*
* @FC0011_FE_CALLBACK_POWER: Power on tuner hardware.
* @FC0011_FE_CALLBACK_RESET: Request a tuner reset.
*/
enum fc0011_fe_callback_commands {
FC0011_FE_CALLBACK_POWER,
FC0011_FE_CALLBACK_RESET,
};
#if IS_REACHABLE(CONFIG_MEDIA_TUNER_FC0011)
struct dvb_frontend *fc0011_attach(struct dvb_frontend *fe,
struct i2c_adapter *i2c,
const struct fc0011_config *config);
#else
static inline
struct dvb_frontend *fc0011_attach(struct dvb_frontend *fe,
struct i2c_adapter *i2c,
const struct fc0011_config *config)
{
dev_err(&i2c->dev, "fc0011 driver disabled in Kconfig\n");
return NULL;
}
#endif
#endif /* LINUX_FC0011_H_ */