Re: [PATCH 12/13] si2157: add on-demand rf strength func

[Antti Palosaari <crope@iki.fi>]

On 12/29/18 7:51 PM, Brad Love wrote:
> Add get_rf_strength callback to get RSSI from the tuner. DVBv5
> stat cache is updated.
> 
> Signed-off-by: Brad Love <brad@nextdimension.cc>


> ---
>   drivers/media/tuners/si2157.c | 38 +++++++++++++++++++++++++++++++++++++-
>   1 file changed, 37 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/tuners/si2157.c b/drivers/media/tuners/si2157.c
> index 1737007..f28bf7f 100644
> --- a/drivers/media/tuners/si2157.c
> +++ b/drivers/media/tuners/si2157.c
> @@ -752,6 +752,40 @@ static int si2157_get_if_frequency(struct dvb_frontend *fe, u32 *frequency)
>   	return 0;
>   }
>   
> +static int si2157_get_rf_strength(struct dvb_frontend *fe, u16 *rssi)
> +{
> +	struct i2c_client *client = fe->tuner_priv;
> +	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
> +	struct si2157_cmd cmd;
> +	int ret;
> +	int strength;
> +
> +	dev_dbg(&client->dev, "\n");
> +
> +	memcpy(cmd.args, "\x42\x00", 2);
> +	cmd.wlen = 2;
> +	cmd.rlen = 12;
> +	ret = si2157_cmd_execute(client, &cmd);
> +	if (ret)
> +		goto err;
> +
> +	c->strength.stat[0].scale = FE_SCALE_DECIBEL;
> +	c->strength.stat[0].svalue = (s8) cmd.args[3] * 1000;
> +
> +	strength = (s8)cmd.args[3];
> +	strength = (strength > -80) ? (u16)(strength + 100) : 0;
> +	strength = strength > 80 ? 100 : strength;
> +
> +	*rssi = (u16)(strength * 0xffff / 100);
> +	dev_dbg(&client->dev, "%s: strength=%d rssi=%u\n",
> +		__func__, (s8)cmd.args[3], *rssi);
> +
> +	return 0;
> +err:
> +	dev_dbg(&client->dev, "failed=%d\n", ret);
> +	return ret;
> +}
> +
>   static const struct dvb_tuner_ops si2157_ops = {
>   	.info = {
>   		.name             = "Silicon Labs Si2141/Si2146/2147/2148/2157/2158",
> @@ -765,7 +799,9 @@ static const struct dvb_tuner_ops si2157_ops = {
>   	.set_analog_params = si2157_set_analog_params,
>   	.get_frequency     = si2157_get_frequency,
>   	.get_bandwidth     = si2157_get_bandwidth,
> -	.get_if_frequency = si2157_get_if_frequency,
> +	.get_if_frequency  = si2157_get_if_frequency,
> +
> +	.get_rf_strength   = si2157_get_rf_strength,
>   };
>   
>   static void si2157_stat_work(struct work_struct *work)
> 

Where that is called from?

It is also hard to read how you convert dBm RSSI value to some other 
scale. There is various clamp() macros for limiting value to desired range.

__func__ should not be passed to dev_ macros, check some manual how to use.

Driver already polls rssi for digital tv, but I assume that is somehow 
related to analog.


regards
Antti

-- 
http://palosaari.fi/