[media] it913x-fe ver 1.10 correct SNR reading from frontend

Correction of reading from frontend and represents
a SNR nonlinear scale of minimum signal to full signal.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/dvb/frontends/it913x-fe.c b/drivers/media/dvb/frontends/it913x-fe.c
index 6d12dccf5ce859d4ee04a09430df01c3e271113f..07c1b4601b1f78fbaf112bb72d505ff7e0318710 100644 (file)
--- a/drivers/media/dvb/frontends/it913x-fe.c
+++ b/drivers/media/dvb/frontends/it913x-fe.c
@@ -53,6 +53,8 @@ struct it913x_fe_state {
        struct ite_config *config;
        u8 i2c_addr;
        u32 frequency;
+       fe_modulation_t constellation;
+       fe_transmit_mode_t transmission_mode;
        u32 crystalFrequency;
        u32 adcFrequency;
        u8 tuner_type;
@@ -496,14 +498,50 @@ static int it913x_fe_read_signal_strength(struct dvb_frontend *fe,
        return 0;
 }
 
-static int it913x_fe_read_snr(struct dvb_frontend *fe, u16* snr)
+static int it913x_fe_read_snr(struct dvb_frontend *fe, u16 *snr)
 {
        struct it913x_fe_state *state = fe->demodulator_priv;
-       int ret = it913x_read_reg_u8(state, SIGNAL_QUALITY);
-       ret = (ret * 0xff) / 0x64;
-       ret |= (ret << 0x8);
-       *snr = ~ret;
-       return 0;
+       int ret;
+       u8 reg[3];
+       u32 snr_val, snr_min, snr_max;
+       u32 temp;
+
+       ret = it913x_read_reg(state, 0x2c, reg, sizeof(reg));
+
+       snr_val = (u32)(reg[2] << 16) | (reg[1] < 8) | reg[0];
+
+       ret |= it913x_read_reg(state, 0xf78b, reg, 1);
+       if (reg[0])
+               snr_val /= reg[0];
+
+       if (state->transmission_mode == TRANSMISSION_MODE_2K)
+               snr_val *= 4;
+       else if (state->transmission_mode == TRANSMISSION_MODE_4K)
+               snr_val *= 2;
+
+       if (state->constellation == QPSK) {
+               snr_min = 0xb4711;
+               snr_max = 0x191451;
+       } else if (state->constellation == QAM_16) {
+               snr_min = 0x4f0d5;
+               snr_max = 0xc7925;
+       } else if (state->constellation == QAM_64) {
+               snr_min = 0x256d0;
+               snr_max = 0x626be;
+       } else
+               return -EINVAL;
+
+       if (snr_val < snr_min)
+               *snr = 0;
+       else if (snr_val < snr_max) {
+               temp = (snr_val - snr_min) >> 5;
+               temp *= 0xffff;
+               temp /= (snr_max - snr_min) >> 5;
+               *snr = (u16)temp;
+       } else
+               *snr = 0xffff;
+
+       return (ret < 0) ? -ENODEV : 0;
 }
 
 static int it913x_fe_read_ber(struct dvb_frontend *fe, u32 *ber)
@@ -530,9 +568,13 @@ static int it913x_fe_get_frontend(struct dvb_frontend *fe,
        if (reg[3] < 3)
                p->u.ofdm.constellation = fe_con[reg[3]];
 
+       state->constellation = p->u.ofdm.constellation;
+
        if (reg[0] < 3)
                p->u.ofdm.transmission_mode = fe_mode[reg[0]];
 
+       state->transmission_mode = p->u.ofdm.transmission_mode;
+
        if (reg[1] < 4)
                p->u.ofdm.guard_interval = fe_gi[reg[1]];
 
@@ -888,5 +930,5 @@ static struct dvb_frontend_ops it913x_fe_ofdm_ops = {
 
 MODULE_DESCRIPTION("it913x Frontend and it9137 tuner");
 MODULE_AUTHOR("Malcolm Priestley tvboxspy@gmail.com");
-MODULE_VERSION("1.09");
+MODULE_VERSION("1.10");
 MODULE_LICENSE("GPL");