linux/drivers/media/tuners/xc4000.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

68 lines
2.1 KiB
C

/*
* Driver for Xceive XC4000 "QAM/8VSB single chip tuner"
*
* Copyright (c) 2007 Steven Toth <stoth@linuxtv.org>
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef __XC4000_H__
#define __XC4000_H__
#include <linux/firmware.h>
struct dvb_frontend;
struct i2c_adapter;
struct xc4000_config {
u8 i2c_address;
/* if non-zero, power management is enabled by default */
u8 default_pm;
/* value to be written to XREG_AMPLITUDE in DVB-T mode (0: no write) */
u8 dvb_amplitude;
/* if non-zero, register 0x0E is set to filter analog TV video output */
u8 set_smoothedcvbs;
/* IF for DVB-T */
u32 if_khz;
};
/* xc4000 callback command */
#define XC4000_TUNER_RESET 0
/* For each bridge framework, when it attaches either analog or digital,
* it has to store a reference back to its _core equivalent structure,
* so that it can service the hardware by steering gpio's etc.
* Each bridge implementation is different so cast devptr accordingly.
* The xc4000 driver cares not for this value, other than ensuring
* it's passed back to a bridge during tuner_callback().
*/
#if IS_REACHABLE(CONFIG_MEDIA_TUNER_XC4000)
extern struct dvb_frontend *xc4000_attach(struct dvb_frontend *fe,
struct i2c_adapter *i2c,
struct xc4000_config *cfg);
#else
static inline struct dvb_frontend *xc4000_attach(struct dvb_frontend *fe,
struct i2c_adapter *i2c,
struct xc4000_config *cfg)
{
printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
return NULL;
}
#endif
#endif