[media] cx24120: Improve cooked signal strength value

Algorithm copied from cx24117.c - it seems to work. Showing 95% on
a signal I know to be somewhere around 74dBuV.

[mchehab@osg.samsung.net: merged two patches, to avoid breaking compilation]
Signed-off-by: Jemma Denson <jdenson@gmail.com>
Signed-off-by: Patrick Boettcher <patrick.boettcher@posteo.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

diff --git a/drivers/media/dvb-frontends/cx24120.c b/drivers/media/dvb-frontends/cx24120.c
index eecfe22..acdda03 100644 (file)
--- a/drivers/media/dvb-frontends/cx24120.c
+++ b/drivers/media/dvb-frontends/cx24120.c
@@ -608,8 +608,8 @@ static void cx24120_get_stats(struct cx24120_state *state)
        struct dvb_frontend *fe = &state->frontend;
        struct dtv_frontend_properties *c = &fe->dtv_property_cache;
        struct cx24120_cmd cmd;
-       int ret, sigstr_h, sigstr_l;
-       u16 u16tmp;
+       int ret;
+       u16 sig;
 
        dev_dbg(&state->i2c->dev, "%s()\n", __func__);
 
@@ -626,18 +626,18 @@ static void cx24120_get_stats(struct cx24120_state *state)
                }
 
                /* raw */
-               sigstr_h = (cx24120_readreg(state, CX24120_REG_SIGSTR_H) >> 6) << 8;
-               sigstr_l = cx24120_readreg(state, CX24120_REG_SIGSTR_L);
-               dev_dbg(&state->i2c->dev, "%s: Signal strength from firmware= 0x%x\n",
-                       __func__, (sigstr_h | sigstr_l));
+               sig = cx24120_readreg(state, CX24120_REG_SIGSTR_H) >> 6;
+               sig = sig << 8;
+               sig |= cx24120_readreg(state, CX24120_REG_SIGSTR_L);
+               dev_dbg(&state->i2c->dev,
+                       "%s: Signal strength from firmware= 0x%x\n",
+                       __func__, sig);
 
                /* cooked */
-               u16tmp = ((sigstr_h | sigstr_l)  << 5) & 0x0000ffff;
-               dev_dbg(&state->i2c->dev, "%s: Signal strength= 0x%x\n",
-                       __func__, u16tmp);
+               sig = -100 * sig + 94324;
 
                c->strength.stat[0].scale = FE_SCALE_RELATIVE;
-               c->strength.stat[0].uvalue = u16tmp;
+               c->strength.stat[0].uvalue = sig;
        } else {
                c->strength.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
        }