Could you test attached patch?
It enhances reception a little bit, you should be able to receive more
weak signals.
I was able to made test setup against modulator. Modulator + attenuator
+ attenuator + TV-stick, where I got picture using Windows driver at
signal level -29dBm whilst on Linux -26.5dBm was needed. With that patch
Linux driver started performing same as Windows.
regards
Antti
On 07/23/2013 12:09 AM, Antti Palosaari wrote:
On 07/19/2013 08:18 PM, Jan Taegert wrote:
Hello,
when the culprit is the e4000 driver but the old driver from
https://github.com/valtri/DVB-Realtek-RTL2832U-2.2.2-10tuner-mod_kernel-3.0.0
worked for me, then must be somewhere there in the driver sources a
solution for the signal issues.
Does it make sense to look for a particular string in the sources? I
don't have any clue of coding but perhaps I can be helpful in this way.
Feel free to look. Those are different drivers and you cannot compare
easily. For my experience you will need huge amount of time and much
luck with that approach.
As I said, the easiest solution is just to took sniffs and copy&paste
generated code until it starts working.
regards
Antti
There are
- tuner_e4000.c
- nim_rtl2832_e4000.c
Thanks,
Jan.
Am 19.07.2013 14:00, schrieb Antti Palosaari:
Hello
It is e4000 driver problem. Someone should take the look what there is
wrong. Someone sent non-working stick for me, but I wasn't able to
reproduce issue. I used modulator to generate signal with just same
parameters he said non-working, but it worked for me. It looks like
e4000 driver does not perform as well as it should.
Maybe I should take Windows XP and Linux, use modulator to find out
signal condition where Windows works but Linux not, took sniffs and
compare registers... But I am busy and help is more than welcome.
regards
Antti
--
http://palosaari.fi/
>From 152273ba5cda6634acbd55ef99f92206bb5a1ff5 Mon Sep 17 00:00:00 2001
From: Antti Palosaari <crope@xxxxxx>
Date: Wed, 24 Jul 2013 08:04:12 +0300
Subject: [PATCH] e4000: implement DC offset correction
Signed-off-by: Antti Palosaari <crope@xxxxxx>
---
drivers/media/tuners/e4000.c | 56 +++++++++++++++++++++++++++++++++++++-------
1 file changed, 48 insertions(+), 8 deletions(-)
diff --git a/drivers/media/tuners/e4000.c b/drivers/media/tuners/e4000.c
index 1b33ed3..a3a9c87 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)
--
1.7.11.7
