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, | |||
502 | u16 *signal_strength) | 502 | u16 *signal_strength) |
503 | { | 503 | { |
504 | struct cx22702_state *state = fe->demodulator_priv; | 504 | struct cx22702_state *state = fe->demodulator_priv; |
505 | u8 reg23; | ||
505 | 506 | ||
506 | u16 rs_ber; | 507 | /* |
507 | rs_ber = cx22702_readreg(state, 0x23); | 508 | * Experience suggests that the strength signal register works as |
508 | *signal_strength = (rs_ber << 8) | rs_ber; | 509 | * follows: |
510 | * - In the absence of signal, value is 0xff. | ||
511 | * - In the presence of a weak signal, bit 7 is set, not sure what | ||
512 | * the lower 7 bits mean. | ||
513 | * - In the presence of a strong signal, the register holds a 7-bit | ||
514 | * value (bit 7 is cleared), with greater values standing for | ||
515 | * weaker signals. | ||
516 | */ | ||
517 | reg23 = cx22702_readreg(state, 0x23); | ||
518 | if (reg23 & 0x80) { | ||
519 | *signal_strength = 0; | ||
520 | } else { | ||
521 | reg23 = ~reg23 & 0x7f; | ||
522 | /* Scale to 16 bit */ | ||
523 | *signal_strength = (reg23 << 9) | (reg23 << 2) | (reg23 >> 5); | ||
524 | } | ||
509 | 525 | ||
510 | return 0; | 526 | return 0; |
511 | } | 527 | } |