Re: [PATCH v2 4/4] [media] dvb-frontends/stv0367: DVB-C signal strength statistics

[Mauro Carvalho Chehab <mchehab@s-opensource.com>]

Em Wed, 21 Jun 2017 21:45:44 +0200
Daniel Scheller <d.scheller.oss@gmail.com> escreveu:

> From: Daniel Scheller <d.scheller@gmx.net>
> 
> Provide QAM/DVB-C signal strength in decibel scale. Values returned from
> stv0367cab_get_rf_lvl() are good but need to be multiplied as they're in
> 1dBm precision.
> 
> Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
> ---
>  drivers/media/dvb-frontends/stv0367.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/drivers/media/dvb-frontends/stv0367.c b/drivers/media/dvb-frontends/stv0367.c
> index d3be25bc1002..bac6707957a3 100644
> --- a/drivers/media/dvb-frontends/stv0367.c
> +++ b/drivers/media/dvb-frontends/stv0367.c
> @@ -2998,6 +2998,25 @@ static int stv0367ddb_set_frontend(struct dvb_frontend *fe)
>  	return -EINVAL;
>  }
>  
> +static void stv0367ddb_read_signal_strength(struct dvb_frontend *fe)
> +{
> +	struct stv0367_state *state = fe->demodulator_priv;
> +	struct dtv_frontend_properties *p = &fe->dtv_property_cache;
> +	s32 signalstrength;
> +
> +	switch (state->activedemod) {
> +	case demod_cab:
> +		signalstrength = stv0367cab_get_rf_lvl(state) * 1000;
> +		break;
> +	default:
> +		p->strength.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
> +		return;
> +	}
> +
> +	p->strength.stat[0].scale = FE_SCALE_DECIBEL;
> +	p->strength.stat[0].uvalue = signalstrength;
> +}
> +
>  static void stv0367ddb_read_snr(struct dvb_frontend *fe)
>  {
>  	struct stv0367_state *state = fe->demodulator_priv;
> @@ -3075,12 +3094,14 @@ static int stv0367ddb_read_status(struct dvb_frontend *fe,
>  
>  	/* stop if demod isn't locked */
>  	if (!(*status & FE_HAS_LOCK)) {
> +		p->strength.stat[0].scale = FE_SCALE_NOT_AVAILABLE;

Requiring full lock for signal strength sounds really wrong.

Are you sure that it won't work without locks?

Regards,
Mauro

>  		p->cnr.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
>  		p->block_error.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
>  		return ret;
>  	}
>  
>  	stv0367ddb_read_snr(fe);
> +	stv0367ddb_read_signal_strength(fe);
>  	stv0367ddb_read_ucblocks(fe);
>  
>  	return 0;



Thanks,
Mauro