Hi Mauro,
thanks for update. I have tested now yours two patches and it works.
dvbv5-zap shows correlated values depends on attenuation on my
modulator. Here is some values i have observed for DVB-T 473Mhz QAM64
8Mhz:
dvbv5-zap, Signal= dBm modulator (teleview TVB590), Amplitude dBm
-89.46dBm modulator stopped (no signal)
-64.30 -57
-62.35 -50
-51.40 -40
-41.33 -30
-38.60 -27
Acked-by: Abylay Ospan <aospan@xxxxxxxx>
2016-06-30 18:41 GMT-04:00 Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>:
> The signal strength value is reversed: the bigger the number,
> the weaker is the signal.
>
> Fix the logic and present it in dBm. Please notice that the
> dBm measure is actually an estimation, as the ratio is not
> fully linear. It also varies with the frequency.
>
> Yet, the estimation should be good enough for programs like
> Kaffeine to indicate when the signal is good or bad.
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
> ---
> drivers/media/dvb-frontends/cxd2841er.c | 31 ++++++++++++++++++-------------
> 1 file changed, 18 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/media/dvb-frontends/cxd2841er.c b/drivers/media/dvb-frontends/cxd2841er.c
> index c1b77a6268d4..c960e8a725cc 100644
> --- a/drivers/media/dvb-frontends/cxd2841er.c
> +++ b/drivers/media/dvb-frontends/cxd2841er.c
> @@ -1727,32 +1727,39 @@ static int cxd2841er_read_ber(struct dvb_frontend *fe, u32 *ber)
> return 0;
> }
>
> -static int cxd2841er_read_signal_strength(struct dvb_frontend *fe,
> - u16 *strength)
> +static void cxd2841er_read_signal_strength(struct dvb_frontend *fe)
> {
> struct dtv_frontend_properties *p = &fe->dtv_property_cache;
> struct cxd2841er_priv *priv = fe->demodulator_priv;
> + u32 strength;
>
> dev_dbg(&priv->i2c->dev, "%s()\n", __func__);
> switch (p->delivery_system) {
> case SYS_DVBT:
> case SYS_DVBT2:
> - *strength = 65535 - cxd2841er_read_agc_gain_t_t2(
> - priv, p->delivery_system);
> - break;
> + strength = cxd2841er_read_agc_gain_t_t2(priv,
> + p->delivery_system);
> + p->strength.stat[0].scale = FE_SCALE_DECIBEL;
> + /* Formula was empirically determinated @ 410 MHz */
> + p->strength.stat[0].uvalue = ((s32)strength) * 366 / 100 - 89520;
> + break; /* Code moved out of the function */
> case SYS_ISDBT:
> - *strength = 65535 - cxd2841er_read_agc_gain_i(
> + strength = 65535 - cxd2841er_read_agc_gain_i(
> priv, p->delivery_system);
> + p->strength.stat[0].scale = FE_SCALE_RELATIVE;
> + p->strength.stat[0].uvalue = strength;
> break;
> case SYS_DVBS:
> case SYS_DVBS2:
> - *strength = 65535 - cxd2841er_read_agc_gain_s(priv);
> + strength = 65535 - cxd2841er_read_agc_gain_s(priv);
> + p->strength.stat[0].scale = FE_SCALE_RELATIVE;
> + p->strength.stat[0].uvalue = strength;
> break;
> default:
> - *strength = 0;
> + p->strength.stat[0].scale = FE_SCALE_RELATIVE;
> + p->strength.stat[0].uvalue = 0;
> break;
> }
> - return 0;
> }
>
> static int cxd2841er_read_snr(struct dvb_frontend *fe, u16 *snr)
> @@ -2926,7 +2933,7 @@ static int cxd2841er_get_frontend(struct dvb_frontend *fe,
> struct dtv_frontend_properties *p)
> {
> enum fe_status status = 0;
> - u16 strength = 0, snr = 0;
> + u16 snr = 0;
> u32 errors = 0, ber = 0;
> struct cxd2841er_priv *priv = fe->demodulator_priv;
>
> @@ -2936,9 +2943,7 @@ static int cxd2841er_get_frontend(struct dvb_frontend *fe,
> else if (priv->state == STATE_ACTIVE_TC)
> cxd2841er_read_status_tc(fe, &status);
>
> - cxd2841er_read_signal_strength(fe, &strength);
> - p->strength.stat[0].scale = FE_SCALE_RELATIVE;
> - p->strength.stat[0].uvalue = strength;
> + cxd2841er_read_signal_strength(fe);
>
> if (status & FE_HAS_LOCK) {
> cxd2841er_read_snr(fe, &snr);
> --
> 2.7.4
>
--
Abylay Ospan,
NetUP Inc.
http://www.netup.tv
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