2.26.Tuner functions and data structures¶

enumtuner_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 aseparate tuner for radio. In any case, the tuner-core needs to know ifthe tuner chip(s) will be used in radio mode or analog TV mode, as, onradio mode, frequencies are specified on a different range than on TVmode. Thisenumis used by the tuner core in order to work with theproper tuner range and eventually use a different tuner chip while inradio mode.

structtuner_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 uniqueidentifier.
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 supportRadio, analog TV and/or digital TV.
config: Used to send tuner-specific configuration for complextuners that require extra parameters to be set.Only a very few tuners require it and its usage onnewer 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 thebridge chipset, in order to do things like resettingthe device.

Description

Older boards only had a single tuner device. Nowadays multiple tunerdevices may be present on a single board. Using TUNER_SET_TYPE_ADDRto pass the tuner_setup structure it is possible to setup each tunerdevice in turn.

Since multiple devices may be present it is no longer sufficient tosend a command to a single i2c device. Instead you should broadcastthe command to all i2c devices.

By setting the mode_mask correctly you can select which commands areaccepted by a specific tuner device. For example, set mode_mask toT_RADIO if the device is a radio-only tuner. That specific tuner willonly accept commands when the tuner is in radio mode and ignore themwhen the tuner is set to TV mode.

enumparam_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

structtuner_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 byV4L2_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 usethose ranges, as they’re defined inside the driver. This is used byanalog tuners that are compatible with the “Philips way” to setup thetuners. 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).

structtuner_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;    const struct tuner_range *ranges;};

Members

type: Type of the tuner parameters, as defined atenumparam_type. If the tuner supports multiplestandards, an array should be used, with onerow per different standard.
cb_first_if_lower_freq: Many Philips-based tuners have a comment intheir datasheet like“For channel selection involving bandswitching, and to ensure smooth tuning to thedesired channel without causing unnecessarycharge pump action, it is recommended toconsider the difference between wanted channelfrequency and the current channel frequency.Unnecessary charge pump action will resultin very low tuning voltage which may drive theoscillator to extreme conditions”.Set cb_first_if_lower_freq to 1, if this checkis required for this tuner. I tested this forPAL by first setting the TV frequency to203 MHz and then switching to 96.6 MHz FMradio. The result was static unless thecontrol 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 selectthe 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 selectthe 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 toselect the FM radio sensitivity. If thissetting is 1, e register will use cGainNormalinstead 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 tobe set to intercarrier mode.
port1_active: This setting sets the default value for PORT1.0 means inactive, 1 means active. Note: theactual bit value written to the tda9887 isinverted. 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: theactual bit value written to the tda9887 isinverted. 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 thisis needed.
port2_invert_for_secam_lc: Sometimes PORT2 is inverted when the SECAM-L’standard is selected. Set this bit to 1 if thisis needed.
port1_set_for_fm_mono: Some cards require PORT1 to be 1 for mono RadioFM and 0 for stereo.
default_pll_gating_18: Select 18% (or according to datasheet 0%)L standard PLL gating, vs the driver defaultof 36%.
radio_if: IF to use in radio mode. Tuners with aseparate radio IF filter seem to use 10.7,while those without use 33.3 for PAL/SECAMtuners 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 lowband. Default is 0. Range: -16:+15
default_top_mid: Default tda9887 TOP value in dB for the midband. Default is 0. Range: -16:+15
default_top_high: Default tda9887 TOP value in dB for the highband. 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 tunersrequire a different TOP value for theSECAM-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 tunersrequire a different TOP value for theSECAM-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 tunersrequire a different TOP value for theSECAM-L/L’ standards. Range: -16:+15
iffreq: Intermediate frequency (IF) used by the tuneron digital mode.
count: Size of the ranges array.
ranges: Array with the frequency ranges supported bythe tuner.

structtunertype¶: describes the known tuners.

Definition:

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

Members

name: string with the tuner’s name.
count: size ofstructtuner_params array.
params: pointer tostructtuner_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.

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2.26.Tuner functions and data structures¶