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Commit 3ff9a81b authored by Hartmut Hackmann's avatar Hartmut Hackmann Committed by Mauro Carvalho Chehab
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V4L/DVB (7656): tda826x: Calculate cut off fequency from symbol rate 



This patch makes the tuner work with transonders providing higher
symbol rates.
It was contributed by Oliver Endriss.

Signed-off-by: default avatarHartmut Hackmann <hartmut.hackmann@t-online.de>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@infradead.org>
parent b1c54fe2

drivers/media/dvb/frontends/tda826x.c

+12 −1
Original line number Diff line number Diff line
@@ -75,6 +75,8 @@ static int tda826x_set_params(struct dvb_frontend *fe, struct dvb_frontend_param 
	struct tda826x_priv *priv = fe->tuner_priv;

	int ret;

	u32 div;

	u32 ksyms;

	u32 bandwidth;

	u8 buf [11];

	struct i2c_msg msg = { .addr = priv->i2c_address, .flags = 0, .buf = buf, .len = 11 };
@@ -82,6 +84,15 @@ static int tda826x_set_params(struct dvb_frontend *fe, struct dvb_frontend_param 


	div = (params->frequency + (1000-1)) / 1000;



	/* BW = ((1 + RO) * SR/2 + 5) * 1.3      [SR in MSPS, BW in MHz] */

	/* with R0 = 0.35 and some transformations: */

	ksyms = params->u.qpsk.symbol_rate / 1000;

	bandwidth = (878 * ksyms + 6500000) / 1000000 + 1;

	if (bandwidth < 5)

		bandwidth = 5;

	else if (bandwidth > 36)

		bandwidth = 36;



	buf[0] = 0x00; // subaddress

	buf[1] = 0x09; // powerdown RSSI + the magic value 1

	if (!priv->has_loopthrough)
@@ -89,7 +100,7 @@ static int tda826x_set_params(struct dvb_frontend *fe, struct dvb_frontend_param 
	buf[2] = (1<<5) | 0x0b; // 1Mhz + 0.45 VCO

	buf[3] = div >> 7;

	buf[4] = div << 1;

	buf[5] = 0x77; // baseband cut-off 19 MHz

	buf[5] = ((bandwidth - 5) << 3) | 7; /* baseband cut-off */

	buf[6] = 0xfe; // baseband gain 9 db + no RF attenuation

	buf[7] = 0x83; // charge pumps at high, tests off

	buf[8] = 0x80; // recommended value 4 for AMPVCO + disable ports.