[media] af9013: cache some reg values to reduce reg reads

Demod + tuner specific RF AGC and IF AGC limit values are read from demod
memory in every signal strength query. Cache those to reduce I2C traffic.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/dvb/frontends/af9013.c b/drivers/media/dvb/frontends/af9013.c
index 6a205e68fde74867a3fedf3d0fd50eb4d2383837..e2a95c07bab421d1b7fff4187d7a05af22d3981b 100644 (file)
--- a/drivers/media/dvb/frontends/af9013.c
+++ b/drivers/media/dvb/frontends/af9013.c
@@ -42,6 +42,8 @@ struct af9013_state {
 
        struct af9013_config config;
 
+       /* tuner/demod RF and IF AGC limits used for signal strength calc */
+       u8 signal_strength_en, rf_50, rf_80, if_50, if_80;
        u16 signal_strength;
        u32 ber;
        u32 ucblocks;
@@ -963,45 +965,31 @@ static int af9013_update_signal_strength(struct dvb_frontend *fe)
 {
        struct af9013_state *state = fe->demodulator_priv;
        int ret;
-       u8 tmp0;
-       u8 rf_gain, rf_50, rf_80, if_gain, if_50, if_80;
+       u8 rf_gain, if_gain;
        int signal_strength;
 
        deb_info("%s\n", __func__);
 
-       state->signal_strength = 0;
-
-       ret = af9013_read_reg_bits(state, 0x9bee, 0, 1, &tmp0);
-       if (ret)
-               goto error;
-       if (tmp0) {
-               ret = af9013_read_reg(state, 0x9bbd, &rf_50);
-               if (ret)
-                       goto error;
-               ret = af9013_read_reg(state, 0x9bd0, &rf_80);
-               if (ret)
-                       goto error;
-               ret = af9013_read_reg(state, 0x9be2, &if_50);
-               if (ret)
-                       goto error;
-               ret = af9013_read_reg(state, 0x9be4, &if_80);
-               if (ret)
-                       goto error;
+       if (state->signal_strength_en) {
                ret = af9013_read_reg(state, 0xd07c, &rf_gain);
                if (ret)
                        goto error;
                ret = af9013_read_reg(state, 0xd07d, &if_gain);
                if (ret)
                        goto error;
-               signal_strength = (0xffff / (9 * (rf_50 + if_50) - \
-                       11 * (rf_80 + if_80))) * (10 * (rf_gain + if_gain) - \
-                       11 * (rf_80 + if_80));
+               signal_strength = (0xffff / \
+                       (9 * (state->rf_50 + state->if_50) - \
+                       11 * (state->rf_80 + state->if_80))) * \
+                       (10 * (rf_gain + if_gain) - \
+                       11 * (state->rf_80 + state->if_80));
                if (signal_strength < 0)
                        signal_strength = 0;
                else if (signal_strength > 0xffff)
                        signal_strength = 0xffff;
 
                state->signal_strength = signal_strength;
+       } else {
+               state->signal_strength = 0;
        }
 
 error:
@@ -1306,6 +1294,27 @@ static int af9013_init(struct dvb_frontend *fe)
        if (ret)
                goto error;
 
+       /* read values needed for signal strength calculation */
+       ret = af9013_read_reg_bits(state, 0x9bee, 0, 1,
+               &state->signal_strength_en);
+       if (ret)
+               goto error;
+
+       if (state->signal_strength_en) {
+               ret = af9013_read_reg(state, 0x9bbd, &state->rf_50);
+               if (ret)
+                       goto error;
+               ret = af9013_read_reg(state, 0x9bd0, &state->rf_80);
+               if (ret)
+                       goto error;
+               ret = af9013_read_reg(state, 0x9be2, &state->if_50);
+               if (ret)
+                       goto error;
+               ret = af9013_read_reg(state, 0x9be4, &state->if_80);
+               if (ret)
+                       goto error;
+       }
+
 error:
        return ret;
 }