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[media] rtl2830: implement .read_snr()

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Reports value as a 0.1 dB.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Antti Palosaari 2012-05-15 18:32:33 -03:00 committed by Mauro Carvalho Chehab
parent f6f379df65
commit eba672a045
2 changed files with 42 additions and 1 deletions
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42
drivers/media/dvb/frontends/rtl2830.c
View file

@ -404,8 +404,48 @@ static int rtl2830_read_status(struct dvb_frontend *fe, fe_status_t *status)
static int rtl2830_read_snr(struct dvb_frontend *fe, u16 *snr)
{
*snr = 0;
struct rtl2830_priv *priv = fe->demodulator_priv;
int ret, hierarchy, constellation;
u8 buf[2], tmp;
u16 tmp16;
#define CONSTELLATION_NUM 3
#define HIERARCHY_NUM 4
static const u32 snr_constant[CONSTELLATION_NUM][HIERARCHY_NUM] = {
{ 70705899, 70705899, 70705899, 70705899 },
{ 82433173, 82433173, 87483115, 94445660 },
{ 92888734, 92888734, 95487525, 99770748 },
};
/* reports SNR in resolution of 0.1 dB */
ret = rtl2830_rd_reg(priv, 0x33c, &tmp);
if (ret)
goto err;
constellation = (tmp >> 2) & 0x03; /* [3:2] */
if (constellation > CONSTELLATION_NUM - 1)
goto err;
hierarchy = (tmp >> 4) & 0x07; /* [6:4] */
if (hierarchy > HIERARCHY_NUM - 1)
goto err;
ret = rtl2830_rd_regs(priv, 0x40c, buf, 2);
if (ret)
goto err;
tmp16 = buf[0] << 8 | buf[1];
if (tmp16)
*snr = (snr_constant[constellation][hierarchy] -
intlog10(tmp16)) / ((1 << 24) / 100);
else
*snr = 0;
return 0;
err:
dbg("%s: failed=%d", __func__, ret);
return ret;
}
static int rtl2830_read_ber(struct dvb_frontend *fe, u32 *ber)

1
drivers/media/dvb/frontends/rtl2830_priv.h
View file

@ -22,6 +22,7 @@
#define RTL2830_PRIV_H
#include "dvb_frontend.h"
#include "dvb_math.h"
#include "rtl2830.h"
#define LOG_PREFIX "rtl2830"