Hi,
Yes, make sense.
2017-06-24 14:35 GMT-04:00 Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>:
> Em Thu, 22 Jun 2017 22:03:28 +0200
> Daniel Scheller <d.scheller.oss@xxxxxxxxx> escreveu:
>
>> From: Daniel Scheller <d.scheller@xxxxxxx>
>>
>> When the demod driver puts the demod into sleep or shutdown state and it's
>> status is then polled e.g. via "dvb-fe-tool -m", i2c errors are printed
>> to the kernel log. If the last delsys was DVB-T/T2:
>>
>> cxd2841er: i2c wr failed=-5 addr=6c reg=00 len=1
>> cxd2841er: i2c rd failed=-5 addr=6c reg=26
>>
>> and if it was DVB-C:
>>
>> cxd2841er: i2c wr failed=-5 addr=6c reg=00 len=1
>> cxd2841er: i2c rd failed=-5 addr=6c reg=49
>>
>> This happens when read_status unconditionally calls into the
>> read_signal_strength() function which triggers the read_agc_gain_*()
>> functions, where these registered are polled.
>>
>> This isn't a critical thing since when the demod is active again, no more
>> such errors are logged, however this might make users suspecting defects.
>>
>> Fix this by requiring fe_status FE_HAS_SYNC to be sure the demod is not
>> put asleep or shut down. If FE_HAS_SYNC isn't set, additionally set the
>> strength scale to NOT_AVAILABLE.
>
> Requiring full lock for signal strength seems too much, as people usually
> rely on signal strength to adjust antenna.
>
> You should, instead, just check if the demod is shut down.
>
> Regards,
> Mauro
>
>>
>> Signed-off-by: Daniel Scheller <d.scheller@xxxxxxx>
>> ---
>> drivers/media/dvb-frontends/cxd2841er.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/media/dvb-frontends/cxd2841er.c b/drivers/media/dvb-frontends/cxd2841er.c
>> index 08f67d60a7d9..9fff031436f1 100644
>> --- a/drivers/media/dvb-frontends/cxd2841er.c
>> +++ b/drivers/media/dvb-frontends/cxd2841er.c
>> @@ -3279,7 +3279,10 @@ 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);
>> + if (status & FE_HAS_SYNC)
>> + cxd2841er_read_signal_strength(fe);
>> + else
>> + p->strength.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
>>
>> if (status & FE_HAS_LOCK) {
>> cxd2841er_read_snr(fe);
>
>
>
> Thanks,
> Mauro
--
Abylay Ospan,
NetUP Inc.
http://www.netup.tv
