diff options
author | Mauro Carvalho Chehab <m.chehab@samsung.com> | 2013-12-15 07:41:20 -0200 |
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committer | Mauro Carvalho Chehab <m.chehab@samsung.com> | 2013-12-19 08:17:43 -0200 |
commit | 70315b3eafabd35ce5f2d43dc82517f66d8ce066 (patch) | |
tree | 74eddbcd1d13c23d07d219648032bd8026283ec4 /drivers/media/dvb-frontends/dib8000.c | |
parent | 5ac64ba12aca3bef18e61c866583155a3bbf81c4 (diff) |
[media] dib8000: Don't let tuner hang due to a call to get_frontend()
Both dvbv5-scan and dvbv5-zap tools call FE_GET_PROPERTY inside the
loop that checks for stats. If the frontend doesn't support DVBv5, it
falls back to call the DVBv5 stats APIs(FE_READ_BER, FE_READ_SIGNAL,
FE_READ_SNR and FE_READ_UNCORRECTED_BLOCKS).
A call to FE_GET_PROPERTY makes dvb-frontend core to call get_frontend().
However, due to a race condition on dib8000 between dib8000_get_frontend
and dib8000_tune, if get_frontend occurs too early, it causes the
tune state machine to fail and not get any lock.
This patch adds a workaround code that makes get_frontend() to just
return if none of the frontends have a SYNC. This change fixed the issue
with dvbv5-scan/dvbv5-zap, but a fine-tuned logic might be needed in
the future, when we implement DVBv5 stats on this frontend.
The procedure to test the bug and the fix is the one below:
1) tune into a non-existing frequency with:
$ dvbv5-zap -I dvbv5 -c non_existing_freqs -m 679142857 -t3
2) tune/lock into an existing frequency with:
$ dvbv5-zap -I dvbv5 -c isdb-test -m 479142857
or
$ dvbv5-scan isdb-test
In this case, 679 MHz carrier doesn't exist. Only 479 MHz does.
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Acked-by: Patrick Boettcher <pboettcher@kernellabs.com>
Diffstat (limited to 'drivers/media/dvb-frontends/dib8000.c')
-rw-r--r-- | drivers/media/dvb-frontends/dib8000.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/drivers/media/dvb-frontends/dib8000.c b/drivers/media/dvb-frontends/dib8000.c index 36c839cabe82..063232afecd6 100644 --- a/drivers/media/dvb-frontends/dib8000.c +++ b/drivers/media/dvb-frontends/dib8000.c @@ -3276,15 +3276,27 @@ static int dib8000_sleep(struct dvb_frontend *fe) return dib8000_set_adc_state(state, DIBX000_SLOW_ADC_OFF) | dib8000_set_adc_state(state, DIBX000_ADC_OFF); } +static int dib8000_read_status(struct dvb_frontend *fe, fe_status_t * stat); + static int dib8000_get_frontend(struct dvb_frontend *fe) { struct dib8000_state *state = fe->demodulator_priv; u16 i, val = 0; - fe_status_t stat; + fe_status_t stat = 0; u8 index_frontend, sub_index_frontend; fe->dtv_property_cache.bandwidth_hz = 6000000; + /* + * If called to early, get_frontend makes dib8000_tune to either + * not lock or not sync. This causes dvbv5-scan/dvbv5-zap to fail. + * So, let's just return if frontend 0 has not locked. + */ + dib8000_read_status(fe, &stat); + if (!(stat & FE_HAS_SYNC)) + return 0; + + dprintk("TMCC lock"); for (index_frontend = 1; (index_frontend < MAX_NUMBER_OF_FRONTENDS) && (state->fe[index_frontend] != NULL); index_frontend++) { state->fe[index_frontend]->ops.read_status(state->fe[index_frontend], &stat); if (stat&FE_HAS_SYNC) { |