linux/drivers/media/dvb-frontends/drxd.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

73 lines
1.8 KiB
C

/*
* drxd.h: DRXD DVB-T demodulator driver
*
* Copyright (C) 2005-2007 Micronas
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 only, as published by the Free Software Foundation.
*
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA
* Or, point your browser to http://www.gnu.org/copyleft/gpl.html
*/
#ifndef _DRXD_H_
#define _DRXD_H_
#include <linux/kconfig.h>
#include <linux/types.h>
#include <linux/i2c.h>
struct drxd_config {
u8 index;
u8 pll_address;
u8 pll_type;
#define DRXD_PLL_NONE 0
#define DRXD_PLL_DTT7520X 1
#define DRXD_PLL_MT3X0823 2
u32 clock;
u8 insert_rs_byte;
u8 demod_address;
u8 demoda_address;
u8 demod_revision;
/* If the tuner is not behind an i2c gate, be sure to flip this bit
or else the i2c bus could get wedged */
u8 disable_i2c_gate_ctrl;
u32 IF;
s16(*osc_deviation) (void *priv, s16 dev, int flag);
};
#if IS_REACHABLE(CONFIG_DVB_DRXD)
extern
struct dvb_frontend *drxd_attach(const struct drxd_config *config,
void *priv, struct i2c_adapter *i2c,
struct device *dev);
#else
static inline
struct dvb_frontend *drxd_attach(const struct drxd_config *config,
void *priv, struct i2c_adapter *i2c,
struct device *dev)
{
printk(KERN_INFO "%s: not probed - driver disabled by Kconfig\n",
__func__);
return NULL;
}
#endif
#endif