2.26. Tuner functions and data structures¶

enum tuner_mode¶: Mode of the tuner

Constants

T_RADIO: Tuner core will work in radio mode
T_ANALOG_TV: Tuner core will work in analog TV mode

Description

Older boards only had a single tuner device, but some devices have a separate tuner for radio. In any case, the tuner-core needs to know if the tuner chip(s) will be used in radio mode or analog TV mode, as, on radio mode, frequencies are specified on a different range than on TV mode. This enum is used by the tuner core in order to work with the proper tuner range and eventually use a different tuner chip while in radio mode.

struct tuner_setup¶: setup the tuner chipsets

Definition:

struct tuner_setup {
    unsigned short  addr;
    unsigned int    type;
    unsigned int    mode_mask;
    void *config;
    int (*tuner_callback)(void *dev, int component, int cmd, int arg);
};

Members

addr: I2C address used to control the tuner device/chipset
type: Type of the tuner, as defined at the TUNER_* macros. Each different tuner model should have an unique identifier.
mode_mask: Mask with the allowed tuner modes: V4L2_TUNER_RADIO, V4L2_TUNER_ANALOG_TV and/or V4L2_TUNER_DIGITAL_TV, describing if the tuner should be used to support Radio, analog TV and/or digital TV.
config: Used to send tuner-specific configuration for complex tuners that require extra parameters to be set. Only a very few tuners require it and its usage on newer tuners should be avoided.
tuner_callback: Some tuners require to call back the bridge driver, in order to do some tasks like rising a GPIO at the bridge chipset, in order to do things like resetting the device.

Description

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.

enum param_type¶: type of the tuner pameters

Constants

TUNER_PARAM_TYPE_RADIO: Tuner params are for FM and/or AM radio
TUNER_PARAM_TYPE_PAL: Tuner params are for PAL color TV standard
TUNER_PARAM_TYPE_SECAM: Tuner params are for SECAM color TV standard
TUNER_PARAM_TYPE_NTSC: Tuner params are for NTSC color TV standard
TUNER_PARAM_TYPE_DIGITAL: Tuner params are for digital TV

struct tuner_range¶: define the frequencies supported by the tuner

Definition:

struct tuner_range {
    unsigned short limit;
    unsigned char config;
    unsigned char cb;
};

Members

limit: Max frequency supported by that range, in 62.5 kHz (TV) or 62.5 Hz (Radio), as defined by V4L2_TUNER_CAP_LOW.
config: Value of the band switch byte (BB) to setup this mode.
cb: Value of the CB byte to setup this mode.

Description

Please notice that digital tuners like xc3028/xc4000/xc5000 don't use those ranges, as they're defined inside the driver. This is used by analog tuners that are compatible with the "Philips way" to setup the tuners. On those devices, the tuner set is done via 4 bytes:

divider byte1 (DB1)

divider byte 2 (DB2)

Control byte (CB)

band switch byte (BB)

Some tuners also have an additional optional Auxiliary byte (AB).

struct tuner_params¶: Parameters to be used to setup the tuner. Those are used by drivers/media/tuners/tuner-types.c in order to specify the tuner properties. Most of the parameters are for tuners based on tda9887 IF-PLL multi-standard analog TV/Radio demodulator, with is very common on legacy analog tuners.

Definition:

struct tuner_params {
    enum param_type type;
    unsigned int cb_first_if_lower_freq:1;
    unsigned int has_tda9887:1;
    unsigned int port1_fm_high_sensitivity:1;
    unsigned int port2_fm_high_sensitivity:1;
    unsigned int fm_gain_normal:1;
    unsigned int intercarrier_mode:1;
    unsigned int port1_active:1;
    unsigned int port2_active:1;
    unsigned int port1_invert_for_secam_lc:1;
    unsigned int port2_invert_for_secam_lc:1;
    unsigned int port1_set_for_fm_mono:1;
    unsigned int default_pll_gating_18:1;
    unsigned int radio_if:2;
    signed int default_top_low:5;
    signed int default_top_mid:5;
    signed int default_top_high:5;
    signed int default_top_secam_low:5;
    signed int default_top_secam_mid:5;
    signed int default_top_secam_high:5;
    u16 iffreq;
    unsigned int count;
    struct tuner_range *ranges;
};

Members

type: Type of the tuner parameters, as defined at enum param_type. If the tuner supports multiple standards, an array should be used, with one row per different standard.
cb_first_if_lower_freq: Many Philips-based tuners have a comment in their datasheet like "For channel selection involving band switching, and to ensure smooth tuning to the desired channel without causing unnecessary charge pump action, it is recommended to consider the difference between wanted channel frequency and the current channel frequency. Unnecessary charge pump action will result in very low tuning voltage which may drive the oscillator to extreme conditions". Set cb_first_if_lower_freq to 1, if this check is required for this tuner. I tested this for PAL by first setting the TV frequency to 203 MHz and then switching to 96.6 MHz FM radio. The result was static unless the control byte was sent first.
has_tda9887: Set to 1 if this tuner uses a tda9887
port1_fm_high_sensitivity: Many Philips tuners use tda9887 PORT1 to select the FM radio sensitivity. If this setting is 1, then set PORT1 to 1 to get proper FM reception.
port2_fm_high_sensitivity: Some Philips tuners use tda9887 PORT2 to select the FM radio sensitivity. If this setting is 1, then set PORT2 to 1 to get proper FM reception.
fm_gain_normal: Some Philips tuners use tda9887 cGainNormal to select the FM radio sensitivity. If this setting is 1, e register will use cGainNormal instead of cGainLow.
intercarrier_mode: Most tuners with a tda9887 use QSS mode. Some (cheaper) tuners use Intercarrier mode. If this setting is 1, then the tuner needs to be set to intercarrier mode.
port1_active: This setting sets the default value for PORT1. 0 means inactive, 1 means active. Note: the actual bit value written to the tda9887 is inverted. So a 0 here means a 1 in the B6 bit.
port2_active: This setting sets the default value for PORT2. 0 means inactive, 1 means active. Note: the actual bit value written to the tda9887 is inverted. So a 0 here means a 1 in the B7 bit.
port1_invert_for_secam_lc: Sometimes PORT1 is inverted when the SECAM-L' standard is selected. Set this bit to 1 if this is needed.
port2_invert_for_secam_lc: Sometimes PORT2 is inverted when the SECAM-L' standard is selected. Set this bit to 1 if this is needed.
port1_set_for_fm_mono: Some cards require PORT1 to be 1 for mono Radio FM and 0 for stereo.
default_pll_gating_18: Select 18% (or according to datasheet 0%) L standard PLL gating, vs the driver default of 36%.
radio_if: IF to use in radio mode. Tuners with a separate radio IF filter seem to use 10.7, while those without use 33.3 for PAL/SECAM tuners and 41.3 for NTSC tuners. 0 = 10.7, 1 = 33.3, 2 = 41.3
default_top_low: Default tda9887 TOP value in dB for the low band. Default is 0. Range: -16:+15
default_top_mid: Default tda9887 TOP value in dB for the mid band. Default is 0. Range: -16:+15
default_top_high: Default tda9887 TOP value in dB for the high band. Default is 0. Range: -16:+15
default_top_secam_low: Default tda9887 TOP value in dB for SECAM-L/L' for the low band. Default is 0. Several tuners require a different TOP value for the SECAM-L/L' standards. Range: -16:+15
default_top_secam_mid: Default tda9887 TOP value in dB for SECAM-L/L' for the mid band. Default is 0. Several tuners require a different TOP value for the SECAM-L/L' standards. Range: -16:+15
default_top_secam_high: Default tda9887 TOP value in dB for SECAM-L/L' for the high band. Default is 0. Several tuners require a different TOP value for the SECAM-L/L' standards. Range: -16:+15
iffreq: Intermediate frequency (IF) used by the tuner on digital mode.
count: Size of the ranges array.
ranges: Array with the frequency ranges supported by the tuner.

struct tunertype¶: describes the known tuners.

Definition:

struct tunertype {
    char *name;
    unsigned int count;
    struct tuner_params *params;
    u16 min;
    u16 max;
    u32 stepsize;
    u8 *initdata;
    u8 *sleepdata;
};

Members

name: string with the tuner's name.
count: size of struct tuner_params array.
params: pointer to struct tuner_params array.
min: minimal tuner frequency, in 62.5 kHz step. should be multiplied to 16 to convert to MHz.
max: minimal tuner frequency, in 62.5 kHz step. Should be multiplied to 16 to convert to MHz.
stepsize: frequency step, in Hz.
initdata: optional byte sequence to initialize the tuner.
sleepdata: optional byte sequence to power down the tuner.

The Linux Kernel

Contents

This Page

2.26. Tuner functions and data structures¶