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V4L/DVB (6656): zl10353: store frequencies in 0.1kHz to eliminate rounding errors

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Whilst reanalysing my formulas I realised it was no longer possible to get the
right values for a 36.1667MHz IF due to rounding problems.

Storing frequencies in units of 0.1kHz makes it possible to calculate these
again correctly.

Signed-off-by: Chris Pascoe <c.pascoe@itee.uq.edu.au>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
This commit is contained in:
Chris Pascoe 2007-11-20 08:17:54 -03:00 committed by Mauro Carvalho Chehab
parent 702a67624e
commit a1dcd9de64
3 changed files with 14 additions and 11 deletions
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2
drivers/media/dvb/dvb-usb/cxusb.c
View File

@ -435,7 +435,7 @@ static struct mt352_config cxusb_mt352_config = {
static struct zl10353_config cxusb_zl10353_xc3028_config = {
.demod_address = 0x0f,
.if2 = 4560,
.if2 = 45600,
.no_tuner = 1,
.parallel_ts = 1,
};

15
drivers/media/dvb/frontends/zl10353.c
View File

@ -123,9 +123,10 @@ static void zl10353_calc_nominal_rate(struct dvb_frontend *fe,
enum fe_bandwidth bandwidth,
u16 *nominal_rate)
{
u32 adc_clock = 45056; /* 45.056 MHz */
u8 bw;
struct zl10353_state *state = fe->demodulator_priv;
u32 adc_clock = 450560; /* 45.056 MHz */
u64 value;
u8 bw;
if (state->config.adc_clock)
adc_clock = state->config.adc_clock;
@ -143,7 +144,9 @@ static void zl10353_calc_nominal_rate(struct dvb_frontend *fe,
break;
}
*nominal_rate = (bw * (1 << 23) / 7 * 125 + adc_clock / 2) / adc_clock;
value = (bw * (u64)10 * (1 << 23) / 7 * 125 + adc_clock / 2);
do_div(value, adc_clock);
*nominal_rate = value;
dprintk("%s: bw %d, adc_clock %d => 0x%x\n",
__FUNCTION__, bw, adc_clock, *nominal_rate);
@ -153,8 +156,8 @@ static void zl10353_calc_input_freq(struct dvb_frontend *fe,
u16 *input_freq)
{
struct zl10353_state *state = fe->demodulator_priv;
u32 adc_clock = 45056; /* 45.056 MHz */
int if2 = 36167; /* 36.167 MHz */
u32 adc_clock = 450560; /* 45.056 MHz */
int if2 = 361667; /* 36.1667 MHz */
int ife;
u64 value;
@ -170,7 +173,7 @@ static void zl10353_calc_input_freq(struct dvb_frontend *fe,
if (ife > adc_clock / 2)
ife = adc_clock - ife;
}
value = 65536ULL * ife + adc_clock / 2;
value = (u64)65536 * ife + adc_clock / 2;
do_div(value, adc_clock);
*input_freq = -value;

8
drivers/media/dvb/frontends/zl10353.h
View File

@ -29,9 +29,9 @@ struct zl10353_config
/* demodulator's I2C address */
u8 demod_address;
/* frequencies in kHz */
int adc_clock; /* default: 45056 */
int if2; /* default: 36167 */
/* frequencies in units of 0.1kHz */
int adc_clock; /* default: 450560 (45.056 MHz) */
int if2; /* default: 361667 (36.1667 MHz) */
/* set if no pll is connected to the secondary i2c bus */
int no_tuner;
@ -50,6 +50,6 @@ static inline struct dvb_frontend* zl10353_attach(const struct zl10353_config *c
printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __FUNCTION__);
return NULL;
}
#endif // CONFIG_DVB_ZL10353
#endif /* CONFIG_DVB_ZL10353 */
#endif /* ZL10353_H */