From 386701892b4821c4d127710fa35b1309c4355bbf Mon Sep 17 00:00:00 2001 From: Joerg Riechardt Date: Sat, 29 Aug 2015 12:02:57 -0300 Subject: [media] stv090x: use lookup tables for carrier/noise ratio The stv090x driver uses the lookup table for signal strength already, with this patch we use the lookup tables for carrier/noise ratio as well. This has the advantage, that values for DVB-S and DVB-S2 are now corresponding, while before they were way off. The values are now proportional to real carrier/noise ratio, while before they were corresponding to register values. So now applications are able to give the user real carrier/noise ratio. Because the output has to be within 0x0000...0xFFFF the three negative values for DVB-S2 are omitted. This is no significant loss, because reception is lost at 7.5 dB already (TT S2-1600, Cine S2), so the negative values are not really important, and also for DVB-S they don´t exist. Signed-off-by: Joerg Riechardt Signed-off-by: Mauro Carvalho Chehab --- drivers/media/dvb-frontends/stv090x.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) (limited to 'drivers/media/dvb-frontends') diff --git a/drivers/media/dvb-frontends/stv090x.c b/drivers/media/dvb-frontends/stv090x.c index b586d2a49737..7ef469c0c866 100644 --- a/drivers/media/dvb-frontends/stv090x.c +++ b/drivers/media/dvb-frontends/stv090x.c @@ -3692,9 +3692,12 @@ static int stv090x_read_cnr(struct dvb_frontend *fe, u16 *cnr) } val /= 16; last = ARRAY_SIZE(stv090x_s2cn_tab) - 1; - div = stv090x_s2cn_tab[0].read - - stv090x_s2cn_tab[last].read; - *cnr = 0xFFFF - ((val * 0xFFFF) / div); + div = stv090x_s2cn_tab[last].real - + stv090x_s2cn_tab[3].real; + val = stv090x_table_lookup(stv090x_s2cn_tab, last, val); + if (val < 0) + val = 0; + *cnr = val * 0xFFFF / div; } break; @@ -3714,9 +3717,10 @@ static int stv090x_read_cnr(struct dvb_frontend *fe, u16 *cnr) } val /= 16; last = ARRAY_SIZE(stv090x_s1cn_tab) - 1; - div = stv090x_s1cn_tab[0].read - - stv090x_s1cn_tab[last].read; - *cnr = 0xFFFF - ((val * 0xFFFF) / div); + div = stv090x_s1cn_tab[last].real - + stv090x_s1cn_tab[0].real; + val = stv090x_table_lookup(stv090x_s1cn_tab, last, val); + *cnr = val * 0xFFFF / div; } break; default: -- cgit v1.2.3-55-g7522