On 06/20/2017 08:45 PM, Daniel Scheller wrote:
From: Daniel Scheller <d.scheller@xxxxxxx>
Add signal-to-noise-ratio as provided by the demodulator in decibel scale.
QAM/DVB-C needs some intlog calculation to have usable dB values, OFDM/
DVB-T values from the demod look alright already and are provided as-is.
Signed-off-by: Daniel Scheller <d.scheller@xxxxxxx>
---
drivers/media/dvb-frontends/stv0367.c | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
diff --git a/drivers/media/dvb-frontends/stv0367.c b/drivers/media/dvb-frontends/stv0367.c
index bb498f942ebd..0b13a407df23 100644
--- a/drivers/media/dvb-frontends/stv0367.c
+++ b/drivers/media/dvb-frontends/stv0367.c
@@ -25,6 +25,8 @@
#include <linux/slab.h>
#include <linux/i2c.h>
+#include "dvb_math.h"
+
#include "stv0367.h"
#include "stv0367_defs.h"
#include "stv0367_regs.h"
@@ -33,6 +35,9 @@
/* Max transfer size done by I2C transfer functions */
#define MAX_XFER_SIZE 64
+/* snr logarithmic calc */
+#define INTLOG10X100(x) ((u32) (((u64) intlog10(x) * 100) >> 24))
+
static int stvdebug;
module_param_named(debug, stvdebug, int, 0644);
@@ -3013,6 +3018,33 @@ static int stv0367ddb_read_status(struct dvb_frontend *fe,
return -EINVAL;
}
+static void stv0367ddb_read_snr(struct dvb_frontend *fe)
+{
+ struct stv0367_state *state = fe->demodulator_priv;
+ struct dtv_frontend_properties *p = &fe->dtv_property_cache;
+ int cab_pwr;
+ u32 regval, tmpval, snrval = 0;
+
+ switch (state->activedemod) {
+ case demod_ter:
+ snrval = stv0367ter_snr_readreg(fe);
+ break;
+ case demod_cab:
+ cab_pwr = stv0367cab_snr_power(fe);
+ regval = stv0367cab_snr_readreg(fe, 0);
+
+ tmpval = (cab_pwr * 320) / regval;
+ snrval = ((tmpval != 0) ? INTLOG10X100(tmpval) : 0) * 100;
How much there will be rounding errors due to that signal/noise
division? I would convert it to calculation of sums (tip logarithm
calculation rules).
Also, that INTLOG10X100 is pretty much useless. Use just what
intlog10/intlog2 offers without yet again another conversion.
+ break;
+ default:
+ p->cnr.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
+ return;
+ }
+
+ p->cnr.stat[0].scale = FE_SCALE_DECIBEL;
+ p->cnr.stat[0].uvalue = snrval;
+}
+
static void stv0367ddb_read_ucblocks(struct dvb_frontend *fe)
{
struct stv0367_state *state = fe->demodulator_priv;
@@ -3069,6 +3101,7 @@ static int stv0367ddb_get_frontend(struct dvb_frontend *fe,
}
stv0367ddb_read_ucblocks(fe);
+ stv0367ddb_read_snr(fe);
return 0;
}
regards
Antti
--
http://palosaari.fi/
