V4L/DVB (6656): zl10353: store frequencies in 0.1kHz to eliminate rounding errors
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>
diff --git a/drivers/media/dvb/frontends/zl10353.c b/drivers/media/dvb/frontends/zl10353.c
index 1736c6a..091fbcc 100644
--- a/drivers/media/dvb/frontends/zl10353.c
+++ b/drivers/media/dvb/frontends/zl10353.c
@@ -123,9 +123,10 @@
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 @@
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 @@
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 @@
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;
