Re: [PATCH v2 1/5] dvb-core: add a new tuner ops to dvb_frontend for APIv5

[Antti Palosaari <crope@iki.fi>]

moikka!

On 08/28/2014 12:07 PM, Akihiro TSUKADA wrote:
> moikka,
> thanks for the comment.
>
>> I have feeling DVBv5 API is aimed to transfer data via property cached.
>> I haven't done much driver for DVBv5 statistics, but recently I
>> implemented CNR (DVBv5 stats) to Si2168 driver and it just writes all
>> the values directly to property cache. I expect RF strength (RSSI) is
>> just similar.
>
> Currently, the demod of PT3 card (tc90522) gets RSSI data from
> the connected tuner (mxl301rf) via tuner_ops.get_signal_strength_dbm()
> and sets property cache in fe->ops.get_frontend() (which is called
> before returning property cache value by dvb_frontend_ioctl_properties()).
> If the tuner driver should set property cache directly,
> when is the right timing to do so?
> In fe->ops.tuner_ops.get_status() ?
> or in the old fe->ops.tuner_ops.get_signal_strength()?
> or Should I change get_signal_strength_dbm(fe, s64 *) to
> update_signal_strength(fe) and let the tuner driver set property cache there?

I think tuner driver should set c->strength as own. Look 
drivers/media/dvb-core/dvb_frontend.c
	/* Fill quality measures */
	case DTV_STAT_SIGNAL_STRENGTH:
		tvp->u.st = c->strength;
		break;

So user-space just get info what is set to struct 
dtv_frontend_properties. That is similarly than CNR and all the other 
statistics.

Start polling thread, which polls once per 2 sec or so, which reads RSSI 
and writes value to struct dtv_frontend_properties. That it is, in my 
understanding. Same for all those DVBv5 stats. Mauro knows better as he 
designed that functionality.

regards
Antti

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