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Commit df61f828 authored by Daniel Scheller's avatar Daniel Scheller Committed by Mauro Carvalho Chehab
Browse files

[media] dvb-frontends/cxd2841er: improved snr reporting 



On DVB-T/T2 at least, SNR might be reported as >2500dB, which not only is
just wrong but also ridiculous, so fix this by improving the conversion
of the register value.

The INTLOG10X100 function/macro and the way the values are converted were
both taken from DD's cxd2843 driver.

Signed-off-by: default avatarDaniel Scheller <d.scheller@gmx.net>
Acked-by: default avatarAbylay Ospan <aospan@netup.ru>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent bf51bbb0

drivers/media/dvb-frontends/cxd2841er.c

+4 −3
Original line number Diff line number Diff line
@@ -38,6 +38,8 @@ 
#define MAX_WRITE_REGSIZE	16

#define LOG2_E_100X 144



#define INTLOG10X100(x) ((u32) (((u64) intlog10(x) * 100) >> 24))



/* DVB-C constellation */

enum sony_dvbc_constellation_t {

	SONY_DVBC_CONSTELLATION_16QAM,
@@ -1817,7 +1819,7 @@ static int cxd2841er_read_snr_t(struct cxd2841er_priv *priv, u32 *snr) 
	}

	if (reg > 4996)

		reg = 4996;

	*snr = 10000 * ((intlog10(reg) - intlog10(5350 - reg)) >> 24) + 28500;

	*snr = 100 * ((INTLOG10X100(reg) - INTLOG10X100(5350 - reg)) + 285);

	return 0;

}
@@ -1846,8 +1848,7 @@ static int cxd2841er_read_snr_t2(struct cxd2841er_priv *priv, u32 *snr) 
	}

	if (reg > 10876)

		reg = 10876;

	*snr = 10000 * ((intlog10(reg) -

		intlog10(12600 - reg)) >> 24) + 32000;

	*snr = 100 * ((INTLOG10X100(reg) - INTLOG10X100(12600 - reg)) + 320);

	return 0;

}