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Commit ef801964 authored by Olivier Grenie's avatar Olivier Grenie Committed by Mauro Carvalho Chehab
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V4L/DVB (12887): DIB7000P: SNR calcuation forr DiB7000P 



Add the SNR monitoring for the dib7000p. The result is in dB.

Signed-off-by: default avatarOlivier Grenie <olivier.grenie@dibcom.fr>
Signed-off-by: default avatarPatrick Boettcher <patrick.boettcher@dibcom.fr>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 74b76f21

drivers/media/dvb/frontends/dib7000p.c

+32 −1
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/kernel.h>

#include <linux/i2c.h>



#include "dvb_math.h"

#include "dvb_frontend.h"



#include "dib7000p.h"
@@ -1217,7 +1218,37 @@ static int dib7000p_read_signal_strength(struct dvb_frontend *fe, u16 *strength) 


static int dib7000p_read_snr(struct dvb_frontend* fe, u16 *snr)

{

	*snr = 0x0000;

	struct dib7000p_state *state = fe->demodulator_priv;

	u16 val;

	s32 signal_mant, signal_exp, noise_mant, noise_exp;

	u32 result = 0;



	val = dib7000p_read_word(state, 479);

	noise_mant = (val >> 4) & 0xff;

	noise_exp = ((val & 0xf) << 2);

	val = dib7000p_read_word(state, 480);

	noise_exp += ((val >> 14) & 0x3);

	if ((noise_exp & 0x20) != 0)

		noise_exp -= 0x40;



	signal_mant = (val >> 6) & 0xFF;

	signal_exp  = (val & 0x3F);

	if ((signal_exp & 0x20) != 0)

		signal_exp -= 0x40;



	if (signal_mant != 0)

		result = intlog10(2) * 10 * signal_exp + 10 *

			intlog10(signal_mant);

	else

		result = intlog10(2) * 10 * signal_exp - 100;



	if (noise_mant != 0)

		result -= intlog10(2) * 10 * noise_exp + 10 *

			intlog10(noise_mant);

	else

		result -= intlog10(2) * 10 * noise_exp - 100;



	*snr = result / ((1 << 24) / 10);

	return 0;

}