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| author | Hartmut Hackmann <hartmut.hackmann@t-online.de> | 2008-04-13 22:41:19 -0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@infradead.org> | 2008-04-24 14:09:44 -0300 |
| commit | 3ff9a81b21c673fd91ad8456242ca68922f77ac4 (patch) | |
| tree | 6fdeec0587c21432139865308d80822e095f7d42 /drivers/media/dvb/frontends/tda826x.c | |
| parent | b1c54fe2aed3e2812f5b42916894f15e84b484b5 (diff) | |
| download | lwn-3ff9a81b21c673fd91ad8456242ca68922f77ac4.tar.gz lwn-3ff9a81b21c673fd91ad8456242ca68922f77ac4.zip | |
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: Hartmut Hackmann <hartmut.hackmann@t-online.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Diffstat (limited to 'drivers/media/dvb/frontends/tda826x.c')
| -rw-r--r-- | drivers/media/dvb/frontends/tda826x.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/drivers/media/dvb/frontends/tda826x.c b/drivers/media/dvb/frontends/tda826x.c index 5a15bb4263fb..a051554b5e25 100644 --- a/drivers/media/dvb/frontends/tda826x.c +++ b/drivers/media/dvb/frontends/tda826x.c @@ -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. |