[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>

1 files changed, 32 insertions, 23 deletions

diff --git a/drivers/media/dvb/frontends/af9013.c b/drivers/media/dvb/frontends/af9013.c
index 6a205e68fde7..e2a95c07bab4 100644
--- 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;
 }