From a544521ef06ee7b8a3d82fa29627401196fda77a Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Mon, 9 Jan 2006 15:25:39 -0200 Subject: V4L/DVB (3245): Added some comments about multiple tuner support. - Added some comments to make clearer how to use ioctl api to handle multiple tuners at the same board. Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- include/media/tuner.h | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) (limited to 'include') diff --git a/include/media/tuner.h b/include/media/tuner.h index aa91ce35915b..c5f034ecb002 100644 --- a/include/media/tuner.h +++ b/include/media/tuner.h @@ -150,10 +150,26 @@ enum tuner_mode { T_STANDBY = 1 << 31 }; +/* Older boards only had a single tuner device. Nowadays multiple tuner + devices may be present on a single board. Using TUNER_SET_TYPE_ADDR + to pass the tuner_setup structure it is possible to setup each tuner + device in turn. + + Since multiple devices may be present it is no longer sufficient to + send a command to a single i2c device. Instead you should broadcast + the command to all i2c devices. + + By setting the mode_mask correctly you can select which commands are + accepted by a specific tuner device. For example, set mode_mask to + T_RADIO if the device is a radio-only tuner. That specific tuner will + only accept commands when the tuner is in radio mode and ignore them + when the tuner is set to TV mode. + */ + struct tuner_setup { - unsigned short addr; - unsigned int type; - unsigned int mode_mask; + unsigned short addr; /* I2C address */ + unsigned int type; /* Tuner type */ + unsigned int mode_mask; /* Allowed tuner modes */ }; struct tuner { -- cgit v1.2.1