From 5279b1ff3699153a53d7ca030b5fb95950001c36 Mon Sep 17 00:00:00 2001 From: Michael Krufky Date: Mon, 31 Oct 2011 08:11:00 -0300 Subject: [PATCH] [media] au8522: Calculate signal strength shown as percentage from SNR up to 35dB As done first in lgdt330x.c, calculate signal strength from SNR up to 35dB Even though the SNR can go higher than 35dB, there is some comfort factor in having a range of strong signals that can show at 100% Signed-off-by: Michael Krufky Signed-off-by: Devin Heitmueller Signed-off-by: Steven Toth Signed-off-by: Mauro Carvalho Chehab --- drivers/media/dvb/frontends/au8522_dig.c | 31 +++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/drivers/media/dvb/frontends/au8522_dig.c b/drivers/media/dvb/frontends/au8522_dig.c index 1d572940e24..5c0d3989f5b 100644 --- a/drivers/media/dvb/frontends/au8522_dig.c +++ b/drivers/media/dvb/frontends/au8522_dig.c @@ -862,7 +862,36 @@ static int au8522_read_snr(struct dvb_frontend *fe, u16 *snr) static int au8522_read_signal_strength(struct dvb_frontend *fe, u16 *signal_strength) { - return au8522_read_snr(fe, signal_strength); + /* borrowed from lgdt330x.c + * + * Calculate strength from SNR up to 35dB + * Even though the SNR can go higher than 35dB, + * there is some comfort factor in having a range of + * strong signals that can show at 100% + */ + u16 snr; + u32 tmp; + int ret = au8522_read_snr(fe, &snr); + + *signal_strength = 0; + + if (0 == ret) { + /* The following calculation method was chosen + * purely for the sake of code re-use from the + * other demod drivers that use this method */ + + /* Convert from SNR in dB * 10 to 8.24 fixed-point */ + tmp = (snr * ((1 << 24) / 10)); + + /* Convert from 8.24 fixed-point to + * scale the range 0 - 35*2^24 into 0 - 65535*/ + if (tmp >= 8960 * 0x10000) + *signal_strength = 0xffff; + else + *signal_strength = tmp / 8960; + } + + return ret; } static int au8522_read_ucblocks(struct dvb_frontend *fe, u32 *ucblocks) -- 2.41.0