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[media] mb86a20s: don't allow updating signal strength too fast

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Getting signal strength requires some loop poking with I2C.
Don't let it happen too fast.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Mauro Carvalho Chehab 2013-03-02 10:15:30 -03:00
parent dad78c5662
commit 0921ecfdc2
1 changed files with 17 additions and 7 deletions
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24
drivers/media/dvb-frontends/mb86a20s.c
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@ -34,6 +34,7 @@ struct mb86a20s_state {
u32 if_freq;
u32 estimated_rate[3];
unsigned long get_strength_time;
bool need_init;
};
@ -318,9 +319,17 @@ static int mb86a20s_read_status(struct dvb_frontend *fe, fe_status_t *status)
static int mb86a20s_read_signal_strength(struct dvb_frontend *fe)
{
struct mb86a20s_state *state = fe->demodulator_priv;
struct dtv_frontend_properties *c = &fe->dtv_property_cache;
int rc;
unsigned rf_max, rf_min, rf;
if (state->get_strength_time &&
(!time_after(jiffies, state->get_strength_time)))
return c->strength.stat[0].uvalue;
/* Reset its value if an error happen */
c->strength.stat[0].uvalue = 0;
/* Does a binary search to get RF strength */
rf_max = 0xfff;
rf_min = 0;
@ -350,15 +359,19 @@ static int mb86a20s_read_signal_strength(struct dvb_frontend *fe)
rf = (rf_max + rf_min) / 2;
/* Rescale it from 2^12 (4096) to 2^16 */
rf <<= (16 - 12);
rf = rf << (16 - 12);
if (rf)
rf |= (1 << 12) - 1;
dev_dbg(&state->i2c->dev,
"%s: signal strength = %d (%d < RF=%d < %d)\n",
__func__, rf, rf_min, rf >> 4, rf_max);
return rf;
c->strength.stat[0].uvalue = rf;
state->get_strength_time = jiffies +
msecs_to_jiffies(1000);
return 0;
}
} while (1);
return 0;
}
static int mb86a20s_get_modulation(struct mb86a20s_state *state,
@ -1882,7 +1895,6 @@ static int mb86a20s_read_status_and_stats(struct dvb_frontend *fe,
fe_status_t *status)
{
struct mb86a20s_state *state = fe->demodulator_priv;
struct dtv_frontend_properties *c = &fe->dtv_property_cache;
int rc, status_nr;
dev_dbg(&state->i2c->dev, "%s called.\n", __func__);
@ -1913,8 +1925,6 @@ static int mb86a20s_read_status_and_stats(struct dvb_frontend *fe,
rc = 0; /* Status is OK */
goto error;
}
/* Fill signal strength */
c->strength.stat[0].uvalue = rc;
if (status_nr >= 7) {
/* Get TMCC info*/