Commit 19bb3b71 authored by Daniel Scheller's avatar Daniel Scheller Committed by Mauro Carvalho Chehab
Browse files

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: default avatarDaniel Scheller <d.scheller@gmx.net>
Tested-by: default avatarRichard Scobie <r.scobie@clear.net.nz>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent ea71c62b

drivers/media/dvb-frontends/stv0910.c

+44 −4
Original line number Diff line number Diff line
@@ -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)

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