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media: dvb-frontends/stv0910: Add demod-only signal strength reporting 

Original code at least has some signed/unsigned issues, resulting in
values like 32dBm. Implement signal strength readout to work without
asking the attached tuner, and use a lookup table instead of log calc.
Values reported appear plausible, gathered from feedback from several
testers.

Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Tested-by: Richard Scobie <r.scobie@clear.net.nz>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Daniel Scheller 2017-07-03 13:20:57 -04:00 committed by Mauro Carvalho Chehab
parent ea71c62bde
commit 19bb3b718f
1 changed files with 44 additions and 4 deletions
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48
drivers/media/dvb-frontends/stv0910.c
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@ -135,7 +135,7 @@ struct sinit_table {
struct slookup {
s16 value;
u16 reg_value;
u32 reg_value;
};
static inline int i2c_write(struct i2c_adapter *adap, u8 adr,
@ -327,6 +327,25 @@ struct slookup s2_sn_lookup[] = {
{ 510, 463 }, /*C/N=51.0dB*/
};
struct slookup padc_lookup[] = {
{ 0, 118000 }, /* PADC=+0dBm */
{ -100, 93600 }, /* PADC=-1dBm */
{ -200, 74500 }, /* PADC=-2dBm */
{ -300, 59100 }, /* PADC=-3dBm */
{ -400, 47000 }, /* PADC=-4dBm */
{ -500, 37300 }, /* PADC=-5dBm */
{ -600, 29650 }, /* PADC=-6dBm */
{ -700, 23520 }, /* PADC=-7dBm */
{ -900, 14850 }, /* PADC=-9dBm */
{ -1100, 9380 }, /* PADC=-11dBm */
{ -1300, 5910 }, /* PADC=-13dBm */
{ -1500, 3730 }, /* PADC=-15dBm */
{ -1700, 2354 }, /* PADC=-17dBm */
{ -1900, 1485 }, /* PADC=-19dBm */
{ -2000, 1179 }, /* PADC=-20dBm */
{ -2100, 1000 }, /* PADC=-21dBm */
};
/*********************************************************************
* Tracking carrier loop carrier QPSK 1/4 to 8PSK 9/10 long Frame
*********************************************************************/
@ -567,7 +586,7 @@ static int tracking_optimization(struct stv *state)
}
static s32 table_lookup(struct slookup *table,
int table_size, u16 reg_value)
int table_size, u32 reg_value)
{
s32 value;
int imin = 0;
@ -1300,11 +1319,32 @@ static int read_ber(struct dvb_frontend *fe)
static void read_signal_strength(struct dvb_frontend *fe)
{
/* FIXME: add signal strength algo */
struct stv *state = fe->demodulator_priv;
struct dtv_frontend_properties *p = &state->fe.dtv_property_cache;
s64 strength;
u8 reg[2];
u16 agc;
s32 padc, power = 0;
int i;
p->strength.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
read_regs(state, RSTV0910_P2_AGCIQIN1 + state->regoff, reg, 2);
agc = (((u32) reg[0]) << 8) | reg[1];
for (i = 0; i < 5; i += 1) {
read_regs(state, RSTV0910_P2_POWERI + state->regoff, reg, 2);
power += (u32) reg[0] * (u32) reg[0]
+ (u32) reg[1] * (u32) reg[1];
usleep_range(3000, 4000);
}
power /= 5;
padc = table_lookup(padc_lookup, ARRAY_SIZE(padc_lookup), power) + 352;
strength = (padc - agc);
p->strength.stat[0].scale = FE_SCALE_DECIBEL;
p->strength.stat[0].uvalue = strength;
}
static int read_status(struct dvb_frontend *fe, enum fe_status *status)