V4L/DVB (10190): cx88: Fix some Kbuild troubles

As Randy Dunlap <randy.dunlap@oracle.com> reported, cx88 has some compilation issues:

drivers/built-in.o: In function `cx88_call_i2c_clients':
(.text+0x20af17): undefined reference to `videobuf_dvb_get_frontend'
drivers/built-in.o: In function `cx8802_probe':
cx88-mpeg.c:(.devinit.text+0x268c4): undefined reference to `videobuf_dvb_alloc_frontend'
cx88-mpeg.c:(.devinit.text+0x268ea): undefined reference to `videobuf_dvb_dealloc_frontends'

With those configs:

CONFIG_VIDEO_CX88=y
CONFIG_VIDEO_CX88_BLACKBIRD=y
CONFIG_VIDEO_CX88_DVB=m
CONFIG_DVB_CORE=m

After carefully examining the code, with the current code, several cx88 drivers
(cx8800, cx8802, cx88_dvb and cx88_blackbird) should be compiled as a module,
if one of them is marked as such. Just fixing Kconfig could create a very complex
set of rules. Also, this hides a problem with the current approach where the dvb
functionality weren't confined inside dvb module.

What happens is that:
	- cx88-i2c (part of cx8800) has some special rules if DVB;
	- cx88-mpeg (cx8802 module) has also part of DVB init code;
	- cx88-dvb has the rest of the dvb code;
	- cx88-blackbird can be used with cx88-mpeg, having cx88-dvb or not.

So, instead of doing some tricks at Kconfig and wait for a next breakage,
this patch moves the dvb code inside cx88-i2c and cx88-mpeg into cx88-dvb.

Another problem is that cx8802 were being compiled, even without cx88-dvb
and cx88-blackbird modules.

While on this code, let's fix also a reported problem:
http://www.linuxtv.org/pipermail/linux-dvb/2009-January/031225.html

A solution for the issue were proposed here:
http://www.mail-archive.com/linux-media@vger.kernel.org/msg00021.html

Thanks to Randy, Andy, Gregoire and Thomas for helping us to detect
and solve the issues.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/drivers/media/video/cx88/cx88-dvb.c b/drivers/media/video/cx88/cx88-dvb.c
index da4dd49..613dfea 100644
--- a/drivers/media/video/cx88/cx88-dvb.c
+++ b/drivers/media/video/cx88/cx88-dvb.c
@@ -138,6 +138,28 @@ static int cx88_dvb_bus_ctrl(struct dvb_frontend* fe, int acquire)
 	return ret;
 }
 
+static void cx88_dvb_gate_ctrl(struct cx88_core  *core, int open)
+{
+	struct videobuf_dvb_frontends *f;
+	struct videobuf_dvb_frontend *fe;
+
+	if (!core->dvbdev)
+		return;
+
+	f = &core->dvbdev->frontends;
+
+	if (!f)
+		return;
+
+	if (f->gate <= 1) /* undefined or fe0 */
+		fe = videobuf_dvb_get_frontend(f, 1);
+	else
+		fe = videobuf_dvb_get_frontend(f, f->gate);
+
+	if (fe && fe->dvb.frontend && fe->dvb.frontend->ops.i2c_gate_ctrl)
+		fe->dvb.frontend->ops.i2c_gate_ctrl(fe->dvb.frontend, open);
+}
+
 /* ------------------------------------------------------------------ */
 
 static int dvico_fusionhdtv_demod_init(struct dvb_frontend* fe)
@@ -597,12 +619,30 @@ static int dvb_register(struct cx8802_dev *dev)
 	struct cx88_core *core = dev->core;
 	struct videobuf_dvb_frontend *fe0, *fe1 = NULL;
 	int mfe_shared = 0; /* bus not shared by default */
+	int i;
 
 	if (0 != core->i2c_rc) {
 		printk(KERN_ERR "%s/2: no i2c-bus available, cannot attach dvb drivers\n", core->name);
 		goto frontend_detach;
 	}
 
+	if (!core->board.num_frontends)
+		return -EINVAL;
+
+	mutex_init(&dev->frontends.lock);
+	INIT_LIST_HEAD(&dev->frontends.felist);
+
+	printk(KERN_INFO "%s() allocating %d frontend(s)\n", __func__,
+			 core->board.num_frontends);
+	for (i = 1; i <= core->board.num_frontends; i++) {
+		fe0 = videobuf_dvb_alloc_frontend(&dev->frontends, i);
+		if (!fe0) {
+			printk(KERN_ERR "%s() failed to alloc\n", __func__);
+			videobuf_dvb_dealloc_frontends(&dev->frontends);
+			goto frontend_detach;
+		}
+	}
+
 	/* Get the first frontend */
 	fe0 = videobuf_dvb_get_frontend(&dev->frontends, 1);
 	if (!fe0)
@@ -611,6 +651,9 @@ static int dvb_register(struct cx8802_dev *dev)
 	/* multi-frontend gate control is undefined or defaults to fe0 */
 	dev->frontends.gate = 0;
 
+	/* Sets the gate control callback to be used by i2c command calls */
+	core->gate_ctrl = cx88_dvb_gate_ctrl;
+
 	/* init frontend(s) */
 	switch (core->boardnr) {
 	case CX88_BOARD_HAUPPAUGE_DVB_T1:
@@ -1109,6 +1152,7 @@ static int dvb_register(struct cx8802_dev *dev)
 		&dev->pci->dev, adapter_nr, mfe_shared);
 
 frontend_detach:
+	core->gate_ctrl = NULL;
 	videobuf_dvb_dealloc_frontends(&dev->frontends);
 	return -EINVAL;
 }
@@ -1270,6 +1314,8 @@ static int cx8802_dvb_remove(struct cx8802_driver *drv)
 
 	vp3054_i2c_remove(dev);
 
+	core->gate_ctrl = NULL;
+
 	return 0;
 }