1 files changed, 10 insertions, 7 deletions

diff --git a/drivers/media/dvb-frontends/cxd2841er.c b/drivers/media/dvb-frontends/cxd2841er.c
index 95d82c4445e2..2476d356069c 100644
--- a/drivers/media/dvb-frontends/cxd2841er.c
+++ b/drivers/media/dvb-frontends/cxd2841er.c
@@ -1746,7 +1746,7 @@ static void cxd2841er_read_signal_strength(struct dvb_frontend *fe)
 {
         struct dtv_frontend_properties *p = &fe->dtv_property_cache;
         struct cxd2841er_priv *priv = fe->demodulator_priv;
-        u32 strength;
+        s32 strength;
 
         dev_dbg(&priv->i2c->dev, "%s()\n", __func__);
         switch (p->delivery_system) {
@@ -1763,7 +1763,7 @@ static void cxd2841er_read_signal_strength(struct dvb_frontend *fe)
                                                         p->delivery_system);
                 p->strength.stat[0].scale = FE_SCALE_DECIBEL;
                 /* Formula was empirically determinated @ 410 MHz */
-                p->strength.stat[0].uvalue = ((s32)strength) * 366 / 100 - 89520;
+                p->strength.stat[0].uvalue = strength * 366 / 100 - 89520;
                 break;  /* Code moved out of the function */
         case SYS_DVBC_ANNEX_A:
                 strength = cxd2841er_read_agc_gain_t_t2(priv,
@@ -1774,13 +1774,16 @@ static void cxd2841er_read_signal_strength(struct dvb_frontend *fe)
                  * using frequencies: 175 MHz, 410 MHz and 800 MHz, and a
                  * stream modulated with QAM64
                  */
-                p->strength.stat[0].uvalue = ((s32)strength) * 4045 / 1000 - 85224;
+                p->strength.stat[0].uvalue = strength * 4045 / 1000 - 85224;
                 break;
         case SYS_ISDBT:
-                strength = 65535 - cxd2841er_read_agc_gain_i(
-                                priv, p->delivery_system);
-                p->strength.stat[0].scale = FE_SCALE_RELATIVE;
-                p->strength.stat[0].uvalue = strength;
+                strength = cxd2841er_read_agc_gain_i(priv, p->delivery_system);
+                p->strength.stat[0].scale = FE_SCALE_DECIBEL;
+                /*
+                 * Formula was empirically determinated via linear regression,
+                 * using frequencies: 175 MHz, 410 MHz and 800 MHz.
+                 */
+                p->strength.stat[0].uvalue = strength * 3775 / 1000 - 90185;
                 break;
         case SYS_DVBS:
         case SYS_DVBS2: