From: Mauro Carvalho Chehab Date: Sun, 15 Dec 2013 09:41:20 +0000 (-0200) Subject: [media] dib8000: Don't let tuner hang due to a call to get_frontend() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=70315b3eafabd35ce5f2d43dc82517f66d8ce066;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git [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 Acked-by: Patrick Boettcher --- 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) {