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-rw-r--r--drivers/media/video/cx88/cx88-tvaudio.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/media/video/cx88/cx88-tvaudio.c b/drivers/media/video/cx88/cx88-tvaudio.c
index 99e120483ec..9aee8c51ee2 100644
--- a/drivers/media/video/cx88/cx88-tvaudio.c
+++ b/drivers/media/video/cx88/cx88-tvaudio.c
@@ -62,6 +62,10 @@ static unsigned int always_analog = 0;
module_param(always_analog,int,0644);
MODULE_PARM_DESC(always_analog,"force analog audio out");
+static unsigned int radio_deemphasis = 0;
+module_param(radio_deemphasis,int,0644);
+MODULE_PARM_DESC(radio_deemphasis, "Radio deemphasis time constant, "
+ "0=None, 1=50us (elsewhere), 2=75us (USA)");
#define dprintk(fmt, arg...) if (audio_debug) \
printk(KERN_DEBUG "%s/0: " fmt, core->name , ## arg)
@@ -678,6 +682,10 @@ static void set_audio_standard_FM(struct cx88_core *core,
};
/* It is enough to leave default values? */
+ /* No, it's not! The deemphasis registers are reset to the 75us
+ * values by default. Analyzing the spectrum of the decoded audio
+ * reveals that "no deemphasis" is the same as 75 us, while the 50 us
+ * setting results in less deemphasis. */
static const struct rlist fm_no_deemph[] = {
{AUD_POLYPH80SCALEFAC, 0x0003},
@@ -688,6 +696,7 @@ static void set_audio_standard_FM(struct cx88_core *core,
set_audio_start(core, SEL_FMRADIO);
switch (deemph) {
+ default:
case FM_NO_DEEMPH:
set_audio_registers(core, fm_no_deemph);
break;
@@ -757,7 +766,7 @@ void cx88_set_tvaudio(struct cx88_core *core)
set_audio_standard_EIAJ(core);
break;
case WW_FM:
- set_audio_standard_FM(core, FM_NO_DEEMPH);
+ set_audio_standard_FM(core, radio_deemphasis);
break;
case WW_NONE:
default: