V4L/DVB (10654): em28xx: VideoMate For You USB TV box requires tvaudio

As reported by Vitaly Wool <vital@embeddedalley.com>:

> about half a year ago I posted the patch that basically enabled Compro
> VideoMate For You USB TV box support.
> The main problem is I couldn't get the sound working.
> So I kind of decomposed the box and found out the audio decoder chip
> used there was Philips TDA9874A. As far as I can see, it's not supported
> within the em28xx suite although it is for other TV tuner drivers.

A tvaudio modprobing confirms that tda9874a chip is accessible via i2c:

tvaudio: TV audio decoder + audio/video mux driver
tvaudio: known chips: tda9840, tda9873h, tda9874h/a, tda9850, tda9855, tea6300, tea6320, tea6420, tda8425, pic16c54 (PV951), ta8874z
tvaudio' 1-0058: chip found @ 0xb0
tvaudio' 1-0058: tvaudio': chip_read2: reg254=0x11
tvaudio' 1-0058: tvaudio': chip_read2: reg255=0x2
tvaudio' 1-0058: tda9874a_checkit(): DIC=0x11, SIC=0x2.
tvaudio' 1-0058: found tda9874a.
tvaudio' 1-0058: tda9874h/a found @ 0xb0 (em28xx #0)
tvaudio' 1-0058: tda9874h/a: chip_write: reg0=0x0
tvaudio' 1-0058: tda9874h/a: chip_write: reg1=0xc0
tvaudio' 1-0058: tda9874h/a: chip_write: reg2=0x2
tvaudio' 1-0058: tda9874h/a: chip_write: reg11=0x80
tvaudio' 1-0058: tda9874h/a: chip_write: reg12=0x0
tvaudio' 1-0058: tda9874h/a: chip_write: reg13=0x0
tvaudio' 1-0058: tda9874h/a: chip_write: reg14=0x1
tvaudio' 1-0058: tda9874h/a: chip_write: reg15=0x0
tvaudio' 1-0058: tda9874h/a: chip_write: reg16=0x14
tvaudio' 1-0058: tda9874h/a: chip_write: reg17=0x50
tvaudio' 1-0058: tda9874h/a: chip_write: reg18=0xf9
tvaudio' 1-0058: tda9874h/a: chip_write: reg19=0x80
tvaudio' 1-0058: tda9874h/a: chip_write: reg20=0x80
tvaudio' 1-0058: tda9874h/a: chip_write: reg24=0x80
tvaudio' 1-0058: tda9874h/a: chip_write: reg255=0x0
tvaudio' 1-0058: tda9874a_setup(): A2, B/G [0x00].
tvaudio' 1-0058: tda9874h/a: thread started]

This patch automatically loads tvaudio when needed (currently, only
with this board).
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/em28xx/em28xx-cards.c

@@ -1244,6 +1244,7 @@ struct em28xx_board em28xx_boards[] = {
 		.tuner_type   = TUNER_LG_PAL_NEW_TAPC,
 		.tda9887_conf = TDA9887_PRESENT,
 		.decoder      = EM28XX_TVP5150,
+		.adecoder     = EM28XX_TVAUDIO,
 		.input        = { {
 			.type     = EM28XX_VMUX_TELEVISION,
 			.vmux     = TVP5150_COMPOSITE0,
@@ -1917,6 +1918,8 @@ void em28xx_card_setup(struct em28xx *dev)
 		request_module("tvp5150");
 	if (dev->board.tuner_type != TUNER_ABSENT)
 		request_module("tuner");
+	if (dev->board.adecoder == EM28XX_TVAUDIO)
+		request_module("tvaudio");
 #endif
 
 	em28xx_config_tuner(dev);

drivers/media/video/em28xx/em28xx.h

@@ -357,6 +357,11 @@ enum em28xx_decoder {
 	EM28XX_SAA711X,
 };
 
+enum em28xx_adecoder {
+	EM28XX_NOADECODER = 0,
+	EM28XX_TVAUDIO,
+};
+
 struct em28xx_board {
 	char *name;
 	int vchannels;
@@ -382,6 +387,7 @@ struct em28xx_board {
 	unsigned char xclk, i2c_speed;
 
 	enum em28xx_decoder decoder;
+	enum em28xx_adecoder adecoder;
 
 	struct em28xx_input       input[MAX_EM28XX_INPUT];
 	struct em28xx_input	  radio;