Em 14-11-2011 16:59, Manu Abraham escreveu:
> On Tue, Nov 15, 2011 at 12:12 AM, Mauro Carvalho Chehab
> <[email protected]> wrote:
>> Em 14-11-2011 16:30, Manu Abraham escreveu:
>>> On Mon, Nov 14, 2011 at 11:38 PM, Mauro Carvalho Chehab
>>> <[email protected]> wrote:
>>>> Yet, this doesn't require any changes at DVB API, as all that the
>>>> demodulator
>>>> need to know is the sub-carrier parameters (frequency, roll-off, symbol
>>>> rate, etc).
>>>
>>> You do: this is why there were changes to the V3 API to accomodate
>>> DVB-S2, which eventually became V5. The major change that underwent is
>>> the addition of newer modulations. The demodulator need to be
>>> explicitly told of the modulation. With some demodulators, the
>>> modulation order could be detected from the PL signaling, rather than
>>> the user space application telling it.
>>
>> DVB-S2 doesn't require DVB bandwidth to be specified.
What I meant to say is that DVB-S2 doesn't require that the bandwidth to be
provided via DVBv5 API.
> stb0899:
> switch (state->delsys) {
> case SYS_DVBS:
> case SYS_DSS:
> ......
> if (state->config->tuner_set_bandwidth)
> state->config->tuner_set_bandwidth(fe, (13 *
> (stb0899_carr_width(state) + SearchRange)) / 10);
> if (state->config->tuner_get_bandwidth)
> state->config->tuner_get_bandwidth(fe,
> &internal->tuner_bw);
> .......
> break;
> case SYS_DVBS2:
> ......
> if (state->config->tuner_set_bandwidth)
> state->config->tuner_set_bandwidth(fe,
> (stb0899_carr_width(state)
> + SearchRange));
> if (state->config->tuner_get_bandwidth)
> state->config->tuner_get_bandwidth(fe,
> &internal->tuner_bw);
> break;
>
>
> cx24116:
>
> /* Set/Reset B/W */
> cmd.args[0x00] = CMD_BANDWIDTH;
> cmd.args[0x01] = 0x01;
> cmd.len = 0x02;
> ret = cx24116_cmd_execute(fe, &cmd);
> if (ret != 0)
> return ret;
>
>
> stv090x does a lot of auto detection for almost everything, but still:
>
> stv090x:
> if (state->algo == STV090x_COLD_SEARCH)
> state->tuner_bw = (15 *
> (stv090x_car_width(state->srate,
> state->rolloff) + 10000000)) / 10;
> else if (state->algo == STV090x_WARM_SEARCH)
> state->tuner_bw =
> stv090x_car_width(state->srate, state->rolloff)
> + 10000000;
> }
Frontends of course need it. The code at stv090x is clear:
state->tuner_bw = stv090x_car_width(state->srate, state->rolloff)
...
static u32 stv090x_car_width(u32 srate, enum stv090x_rolloff rolloff)
{
u32 ro;
switch (rolloff) {
case STV090x_RO_20:
ro = 20;
break;
case STV090x_RO_25:
ro = 25;
break;
case STV090x_RO_35:
default:
ro = 35;
break;
}
return srate + (srate * ro) / 100;
}
Regards,
Mauro
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