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 <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@brturbo.com.br>
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@ -150,10 +150,26 @@ enum tuner_mode {
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T_STANDBY = 1 << 31
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};
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/* Older boards only had a single tuner device. Nowadays multiple tuner
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devices may be present on a single board. Using TUNER_SET_TYPE_ADDR
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to pass the tuner_setup structure it is possible to setup each tuner
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device in turn.
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Since multiple devices may be present it is no longer sufficient to
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send a command to a single i2c device. Instead you should broadcast
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the command to all i2c devices.
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By setting the mode_mask correctly you can select which commands are
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accepted by a specific tuner device. For example, set mode_mask to
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T_RADIO if the device is a radio-only tuner. That specific tuner will
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only accept commands when the tuner is in radio mode and ignore them
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when the tuner is set to TV mode.
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*/
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struct tuner_setup {
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unsigned short addr;
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unsigned int type;
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unsigned int mode_mask;
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unsigned short addr; /* I2C address */
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unsigned int type; /* Tuner type */
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unsigned int mode_mask; /* Allowed tuner modes */
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};
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struct tuner {
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