[linux-dvb] Problem with latest v4l-dvb hg

hermann pitton hermann-pitton at arcor.de
Sun Jun 8 03:00:03 CEST 2008


Am Samstag, den 07.06.2008, 13:42 +0800 schrieb timf:
> timf wrote:
> > Mauro Carvalho Chehab wrote:
> >   
> >> On Fri, 06 Jun 2008 22:59:10 +0200
> >> hermann pitton <hermann-pitton at arcor.de> wrote:
> >>
> >>   
> >>     
> >>> Hi,
> >>>
> >>> Am Samstag, den 07.06.2008, 03:00 +0800 schrieb timf:
> >>>     
> >>>       
> <snip>
> 
> Hi all,
> 
> Something very strange:
> If in saa7134-dvb.c I do this:
> 
> <snip>
> static int configure_tda827x_fe_kw210(struct saa7134_dev *dev,
>                 struct tda1004x_config *cdec_conf,
>                 struct tda827x_config *tuner_conf)
> {
>     dev->dvb.frontend = dvb_attach(tda10046_attach, cdec_conf, 
> &dev->i2c_adap);
>     if (dev->dvb.frontend) {
> /*        if (cdec_conf->i2c_gate)
>             dev->dvb.frontend->ops.i2c_gate_ctrl = tda8290_i2c_gate_ctrl; */
>         if (dvb_attach(tda827x_attach, dev->dvb.frontend,
>                    cdec_conf->tuner_address,
>                    &dev->i2c_adap, tuner_conf))
>             return 0;
> 
>         wprintk("no tda827x tuner found at addr: %02x\n",
>                 cdec_conf->tuner_address);
>     }
>     return -EINVAL;
> }
> <snip>
>     case SAA7134_BOARD_KWORLD_DVBT_210:
> /*        if (configure_tda827x_fe(dev, &kworld_dvb_t_210_config, */
>         if (configure_tda827x_fe_kw210(dev, &kworld_dvb_t_210_config,
>                      &tda827x_cfg_2) < 0)
>             goto dettach_frontend;
>         break;
> <snip>
> then I can scan all available DVB-T channels, and view them.
> If I leave it as original, it won't scan/view SBS.
> 
> Can someone tell me what part does this play?
> 
>         if (cdec_conf->i2c_gate)
>             dev->dvb.frontend->ops.i2c_gate_ctrl = tda8290_i2c_gate_ctrl;

Tim,

without looking in any detail, choosed to have enough for myself.

Almost all, but not all, use the tda8290 analog IF demodulator within
the saa7131e, on prior saa7135 stuff also present as a sepatate chip,
as an i2c bridge to control the tuner, also if in DVB-T mode ...

To deminish interference on the bus, it is only opened to send the
tuning bytes and then closed again.

IIRC, on your card are two tda8275a, which could serve as hybrid tuners,
but on that early design it was choosen to burn some money in favor to
have a first analog and DVB-T at once solution.

Since you have two tuners, you are not depending on the DVB-T gate stuff
for DVB-T, which is a point for swichting issues from analog to DVB else
on single hybrid tuners. To have a digital tuner controlled from the
analog IF demod some still don't get and cause a lot of trouble.

Cheers,
Hermann

> I use this:
> # Australia / Perth (Roleystone transmitter)
> # T freq bw fec_hi fec_lo mod transmission-mode guard-interval hierarchy
> # SBS
> T 704500000 7MHz 2/3 NONE QAM64 8k 1/8 NONE
> # ABC
> T 725500000 7MHz 3/4 NONE QAM64 8k 1/16 NONE
> # Seven
> T 746500000 7MHz 2/3 NONE QAM64 8k 1/16 NONE
> # Nine
> T 767500000 7MHz 3/4 NONE QAM64 8k 1/16 NONE
> # Ten
> T 788500000 7MHz 3/4 NONE QAM64 8k 1/16 NONE
> 
> Regards,
> Timf




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