Re: [RFC PATCH] saa7134: Add AverMedia Satelllite Hybrid+FM A706 (and FM radio problems)

[Ondrej Zary <linux@rainbow-software.org>]

On Tuesday 15 January 2013 22:57:06 Ondrej Zary wrote:
> On Monday 14 January 2013 22:29:58 Ondrej Zary wrote:
> > On Saturday 12 January 2013 21:24:50 Ondrej Zary wrote:
> > > Partially working: FM radio
> > > Radio seems to be a long-standing problem with saa7134 cards using
> > > silicon tuners (according to various mailing lists).
> > >
> > > On this card, GPIO11 controls 74HC4052 MUX. It switches two things:
> > > something at TDA18271 V_IFAGC pin and something that goes to SAA7131E.
> > > GPIO11 is enabled for radio and disabled for TV in Windows. I did the
> > > same thing in this patch.
> > >
> > > Windows INF file says:
> > > ; Setting FM radio of the Silicon tuner via SIF (GPIO 21 in use/
> > > 5.5MHz) HKR, "Audio", "FM Radio IF", 0x00010001, 0xDEEAAB
> > >
> > > But that seems not to be true. GPIO21 does nothing and RegSpy (from
> > > DScaler, modified to include 0x42c register) says that the register is
> > > 0x80729555. That matches the value present in saa7134-tvaudio.c (except
> > > the first 0x80).
> > >
> > > With this value, the radio stations are off by about 4.2-4.3 MHz, e.g.:
> > > station at 97.90 MHz is tuned as 102.20 MHz
> > > station at 101.80 MHz is tuned as 106.0 MHz
> > >
> > > I also tried 0xDEEAAB. With this, the offset is different, about 0.4
> > > MHz: station at 101.80 MHz is tuned as 102.2 MHz
> >
> > The offset seems bogus, maybe affected by my TV antenna (cable).
> >
> > For debugging, tried another card with similar chips: Pinnacle PCTV
> > 40i/50i/110i. It has SAA7131E chip too, but different tuner - TDA8275A.
> > And the radio problem is the same as found first on the A706 - the tuned
> > station sound starts but then turns into noise. So it seems that the
> > problem is not in tda18271 but in tda8290 or saa7134.
> >
> > With tda8290.debug=1, I see this:
> > tda829x 2-004b: tda8290 not locked, no signal?
> > tda829x 2-004b: tda8290 not locked, no signal?
> > tda829x 2-004b: tda8290 not locked, no signal?
> > tda829x 2-004b: adjust gain, step 1. Agc: 193, ADC stat: 255, lock: 0
> > tda829x 2-004b: adjust gain, step 2. Agc: 255, lock: 0
> > tda829x 2-004b: adjust gain, step 3. Agc: 173
> >
> > During that, the sound is good. Then it turns into noise.
> > When I increased the number of lock detections in tda8290_set_params()
> > from 3 to (e.g.) 10, it works longer. And when I'm quick enough to stop
> > the console output using scroll lock, the radio remains working.
>
> Pinnacle radio problems turned out to be a different bug - the driver turns
> off tuners when the radio device is closed - and I was testing using
> v4l2-ctl. Fixing that allows Pinnacle to work fine.
>
> But it's not enough for A706 to work. When I disable gain adjust in tda8290
> (by putting a return before), strong stations work somehow (with noise).

Changing IF frequency from 1.25MHz (1250) to 5.5MHz (5500) in tda18271-maps.c 
allows the radio to work without disabling gain adjust. Seems that IF 
mismatch between tda18271 and saa7134 is causing problems. However, only 
strong stations work.

-- 
Ondrej Zary