diff options
Diffstat (limited to 'drivers/media/dvb/frontends/cx22702.c')
| -rw-r--r-- | drivers/media/dvb/frontends/cx22702.c | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/drivers/media/dvb/frontends/cx22702.c b/drivers/media/dvb/frontends/cx22702.c index faba82485086..edc8eafc5c09 100644 --- a/drivers/media/dvb/frontends/cx22702.c +++ b/drivers/media/dvb/frontends/cx22702.c @@ -502,10 +502,26 @@ static int cx22702_read_signal_strength(struct dvb_frontend *fe, u16 *signal_strength) { struct cx22702_state *state = fe->demodulator_priv; + u8 reg23; - u16 rs_ber; - rs_ber = cx22702_readreg(state, 0x23); - *signal_strength = (rs_ber << 8) | rs_ber; + /* + * Experience suggests that the strength signal register works as + * follows: + * - In the absence of signal, value is 0xff. + * - In the presence of a weak signal, bit 7 is set, not sure what + * the lower 7 bits mean. + * - In the presence of a strong signal, the register holds a 7-bit + * value (bit 7 is cleared), with greater values standing for + * weaker signals. + */ + reg23 = cx22702_readreg(state, 0x23); + if (reg23 & 0x80) { + *signal_strength = 0; + } else { + reg23 = ~reg23 & 0x7f; + /* Scale to 16 bit */ + *signal_strength = (reg23 << 9) | (reg23 << 2) | (reg23 >> 5); + } return 0; } |