From c6e62a3a398d62e8ae366ac1465911db0ac7fc0b Mon Sep 17 00:00:00 2001 From: Chris Pascoe Date: Tue, 20 Nov 2007 02:49:41 -0300 Subject: V4L/DVB (6654): mt352: support oversampled IF input Rework the input frequency calculation so that it produces the right values when the ADC oversamples the IF input. This means MT352 devices can now process a near-zero IF (according to the, specs 4.57MHz is supported with the default crystal). Signed-off-by: Chris Pascoe Signed-off-by: Mauro Carvalho Chehab --- drivers/media/dvb/frontends/mt352.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'drivers/media/dvb') diff --git a/drivers/media/dvb/frontends/mt352.c b/drivers/media/dvb/frontends/mt352.c index 5dd9b731f6f..7cd190b6f01 100644 --- a/drivers/media/dvb/frontends/mt352.c +++ b/drivers/media/dvb/frontends/mt352.c @@ -152,7 +152,13 @@ static void mt352_calc_input_freq(struct mt352_state* state, if (state->config.if2) if2 = state->config.if2; - ife = (2*adc_clock - if2); + if (adc_clock >= if2 * 2) + ife = if2; + else { + ife = adc_clock - (if2 % adc_clock); + if (ife > adc_clock / 2) + ife = adc_clock - ife; + } value = -16374 * ife / adc_clock; dprintk("%s: if2 %d, ife %d, adc_clock %d => %d / 0x%x\n", __FUNCTION__, if2, ife, adc_clock, value, value & 0x3fff); -- cgit v1.2.3