Hello
I did some review and testing. Before that patch, IT9133 DVBv3 signal
strength measurement was broken - it returned 0xffff all the time. After
that is returns some realistic values between 0-0xffff.
Anyhow, AF9033 chip version it worked earlier too, just like old comment
says hw returns 0-100, which was scaled to 0-0xffff.
AF9033 and IT9133 firmware differs on signal strength measurement. For
AF9033 it provides both percentage and dBm reports, for IT9133 I know
only dBm report.
AF9033:
0x800048 relative (0-100, percentage)
0x80004a decibel (-VAL dBm)
IT9133:
0x8000f7 decibel (VAL - 100 dBm)
Now you changed that AF9033 implementation from 0x800048 (percentage) to
0x80004a (dBm) and scale that to 0-0xffff, which results poorer result
than old implementation calculated by firmware.
What I tested that implementation, it gives maximum value 0x6e14, which
we could calc is 43dBm. I was using -18dBm RF level (which is very very
strong), so I suspect that 43dBm is maximum what firmware even could
report. Having maximum possible signal strength only 43% (out of 100%)
is not nice.
So I ask you change AF9035 as it has been (percentage reported by FW).
Change only non-working IT9135 what you like.
Also, add error checking just after register reads and jump out if fails.
regards
Antti
On 10/02/2014 08:32 AM, Bimow Chen wrote:
Register 0x800048 is not dB measure but relative scale. Fix it and conform to NorDig specifications.
0001-af9033-fix-DVBv3-signal-strength-value-not-correct-i.patch
From 02ee7de4600a43a322f75cf04d273effa04d3a42 Mon Sep 17 00:00:00 2001
From: Bimow Chen<Bimow.Chen@xxxxxxxxxx>
Date: Wed, 1 Oct 2014 18:28:54 +0800
Subject: [PATCH 1/2] af9033: fix DVBv3 signal strength value not correct issue
Register 0x800048 is not dB measure but relative scale. Fix it and conform to NorDig specifications.
Signed-off-by: Bimow Chen<Bimow.Chen@xxxxxxxxxx>
---
drivers/media/dvb-frontends/af9033.c | 43 +++++++++++++++++++++++-----
drivers/media/dvb-frontends/af9033_priv.h | 6 ++++
2 files changed, 41 insertions(+), 8 deletions(-)
diff --git a/drivers/media/dvb-frontends/af9033.c b/drivers/media/dvb-frontends/af9033.c
index 63a89c1..2b3d2f0 100644
--- a/drivers/media/dvb-frontends/af9033.c
+++ b/drivers/media/dvb-frontends/af9033.c
@@ -862,16 +862,43 @@ static int af9033_read_snr(struct dvb_frontend *fe, u16 *snr)
static int af9033_read_signal_strength(struct dvb_frontend *fe, u16 *strength)
{
struct af9033_dev *dev = fe->demodulator_priv;
- int ret;
- u8 strength2;
+ struct dtv_frontend_properties *c = &dev->fe.dtv_property_cache;
+ int ret, tmp, power_real;
+ u8 u8tmp, gain_offset, buf[7];
- /* read signal strength of 0-100 scale */
- ret = af9033_rd_reg(dev, 0x800048, &strength2);
- if (ret < 0)
- goto err;
+ if (dev->is_af9035) {
+ ret = af9033_rd_reg(dev, 0x80004a, &u8tmp);
+ /* scale value to 0x0000-0xffff */
+ *strength = u8tmp * 0xffff / 100;
+ } else {
+ ret = af9033_rd_reg(dev, 0x8000f7, &u8tmp);
+ ret |= af9033_rd_regs(dev, 0x80f900, buf, 7);
+
+ if (c->frequency <= 300000000)
+ gain_offset = 7; /* VHF */
+ else
+ gain_offset = 4; /* UHF */
+
+ power_real = (u8tmp - 100 - gain_offset) -
+ power_reference[((buf[3] >> 0) & 3)][((buf[6] >> 0) & 7)];
+
+ if (power_real < -15)
+ tmp = 0;
+ else if ((power_real >= -15) && (power_real < 0))
+ tmp = (2 * (power_real + 15)) / 3;
+ else if ((power_real >= 0) && (power_real < 20))
+ tmp = 4 * power_real + 10;
+ else if ((power_real >= 20) && (power_real < 35))
+ tmp = (2 * (power_real - 20)) / 3 + 90;
+ else
+ tmp = 100;
+
+ /* scale value to 0x0000-0xffff */
+ *strength = tmp * 0xffff / 100;
+ }
- /* scale value to 0x0000-0xffff */
- *strength = strength2 * 0xffff / 100;
+ if (ret)
+ goto err;
return 0;
diff --git a/drivers/media/dvb-frontends/af9033_priv.h b/drivers/media/dvb-frontends/af9033_priv.h
index c12c92c..c9c8798 100644
--- a/drivers/media/dvb-frontends/af9033_priv.h
+++ b/drivers/media/dvb-frontends/af9033_priv.h
@@ -2051,4 +2051,10 @@ static const struct reg_val tuner_init_it9135_62[] = {
{ 0x80fd8b, 0x00 },
};
+/* NorDig power reference table */
+static const int power_reference[][5] = {
+ {-93, -91, -90, -89, -88}, /* QPSK 1/2 ~ 7/8 */
+ {-87, -85, -84, -83, -82}, /* 16QAM 1/2 ~ 7/8 */
+ {-82, -80, -78, -77, -76}, /* 64QAM 1/2 ~ 7/8 */
+};
#endif /* AF9033_PRIV_H */
-- 1.7.0.4
--
http://palosaari.fi/
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