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| author | Antti Palosaari <crope@iki.fi> | 2013-07-24 02:04:12 -0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <m.chehab@samsung.com> | 2013-08-18 07:52:50 -0300 |
| commit | 8514611438e9e324a9faeac69393c62ef76a5832 (patch) | |
| tree | 450bd4f3ab04b740366286c6e3ae3a041724544d /drivers/media/tuners | |
| parent | 83453a7cc8b703ce818c24c2298822b0b179e652 (diff) | |
| download | linux-8514611438e9e324a9faeac69393c62ef76a5832.tar.gz linux-8514611438e9e324a9faeac69393c62ef76a5832.tar.bz2 linux-8514611438e9e324a9faeac69393c62ef76a5832.zip | |
[media] e4000: implement DC offset correction
I did some tests against modulator (television signal generator) and this
seems to improve sensitivity a little bit on channel I used. Used device
was able to receive transmission just as weak signal as with Windows XP.
Thanks to Jacek for donating his non-working device. I cannot ask he to
test anymore...
Reported-by: Jacek Konieczny <jajcus@jajcus.net>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Diffstat (limited to 'drivers/media/tuners')
| -rw-r--r-- | drivers/media/tuners/e4000.c | 56 |
1 files changed, 48 insertions, 8 deletions
diff --git a/drivers/media/tuners/e4000.c b/drivers/media/tuners/e4000.c index 1b33ed368abe..a3a9c87a472b 100644 --- a/drivers/media/tuners/e4000.c +++ b/drivers/media/tuners/e4000.c @@ -140,14 +140,12 @@ static int e4000_init(struct dvb_frontend *fe) if (ret < 0) goto err; - /* - * TODO: Implement DC offset control correctly. - * DC offsets has quite much effect for received signal quality in case - * of direct conversion tuners (Zero-IF). Surely we will now lose few - * decimals or even decibels from SNR... - */ /* DC offset control */ - ret = e4000_wr_reg(priv, 0x2d, 0x0c); + ret = e4000_wr_reg(priv, 0x2d, 0x1f); + if (ret < 0) + goto err; + + ret = e4000_wr_regs(priv, 0x70, "\x01\x01", 2); if (ret < 0) goto err; @@ -204,7 +202,7 @@ static int e4000_set_params(struct dvb_frontend *fe) struct dtv_frontend_properties *c = &fe->dtv_property_cache; int ret, i, sigma_delta; unsigned int f_VCO; - u8 buf[5]; + u8 buf[5], i_data[4], q_data[4]; dev_dbg(&priv->i2c->dev, "%s: delivery_system=%d frequency=%d " \ "bandwidth_hz=%d\n", __func__, @@ -292,6 +290,48 @@ static int e4000_set_params(struct dvb_frontend *fe) if (ret < 0) goto err; + /* DC offset */ + for (i = 0; i < 4; i++) { + if (i == 0) + ret = e4000_wr_regs(priv, 0x15, "\x00\x7e\x24", 3); + else if (i == 1) + ret = e4000_wr_regs(priv, 0x15, "\x00\x7f", 2); + else if (i == 2) + ret = e4000_wr_regs(priv, 0x15, "\x01", 1); + else + ret = e4000_wr_regs(priv, 0x16, "\x7e", 1); + + if (ret < 0) + goto err; + + ret = e4000_wr_reg(priv, 0x29, 0x01); + if (ret < 0) + goto err; + + ret = e4000_rd_regs(priv, 0x2a, buf, 3); + if (ret < 0) + goto err; + + i_data[i] = (((buf[2] >> 0) & 0x3) << 6) | (buf[0] & 0x3f); + q_data[i] = (((buf[2] >> 4) & 0x3) << 6) | (buf[1] & 0x3f); + } + + buf[0] = q_data[0]; + buf[1] = q_data[1]; + buf[2] = q_data[3]; + buf[3] = q_data[2]; + ret = e4000_wr_regs(priv, 0x50, buf, 4); + if (ret < 0) + goto err; + + buf[0] = i_data[0]; + buf[1] = i_data[1]; + buf[2] = i_data[3]; + buf[3] = i_data[2]; + ret = e4000_wr_regs(priv, 0x60, buf, 4); + if (ret < 0) + goto err; + /* gain control auto */ ret = e4000_wr_reg(priv, 0x1a, 0x17); if (ret < 0) |