Avoid radio interference from the MAS internal clock on devices with the Samsung tuner (FM recorder, old Ondio FM) by slightly shifting it away when necessary.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@6531 a1c6a512-1295-4272-9138-f99709370657

firmware/export/mpeg.h

@@ -50,6 +50,9 @@ void mpeg_set_recording_options(int frequency, int quality,
                                 int source, int channel_mode,
                                 bool editable, int prerecord_time);
 void mpeg_set_recording_gain(int left, int right, bool use_mic);
+#if CONFIG_TUNER & S1A0903X01
+int mpeg_get_mas_pllfreq(void);
+#endif
 unsigned long mpeg_recorded_time(void);
 unsigned long mpeg_num_recorded_bytes(void);
 void mpeg_pause_recording(void);

firmware/mpeg.c

@@ -2382,6 +2382,22 @@ void mpeg_set_recording_gain(int left, int right, bool use_mic)
     mas_codec_writereg(0x0, shadow_codec_reg0);
 }
 
+#if CONFIG_TUNER & S1A0903X01
+/* Get the (unpitched) MAS PLL frequency, for avoiding FM interference with the
+ * Samsung tuner. Zero means unknown. Currently handles recording from analog
+ * input only. */
+int mpeg_get_mas_pllfreq(void)
+{
+    if (mpeg_mode != MPEG_ENCODER)
+        return 0;
+
+    if (rec_frequency_index == 0)  /* 44.1 kHz / 22.05 kHz */
+        return 22579000;
+    else
+        return 24576000;
+}
+#endif
+
 /* try to make some kind of beep, also in recording mode */
 void audio_beep(int duration)
 {

firmware/tuner_samsung.c

@@ -20,8 +20,11 @@
 
 #include <stdbool.h>
 #include <stdlib.h>
+#include "config.h"
 #include "tuner.h" /* tuner abstraction interface */
 #include "fmradio.h" /* physical interface driver */
+#include "mpeg.h"
+#include "sound.h"
 
 #define DEFAULT_IN1 0x100003 /* Mute */
 #define DEFAULT_IN2 0x140884 /* 5kHz, 7.2MHz crystal */
@@ -49,6 +52,28 @@ void samsung_set(int setting, int value)
         case RADIO_FREQUENCY:
         {
             int pll_cnt;
+#if CONFIG_HWCODEC == MAS3587F
+            /* Shift the MAS internal clock away for certain frequencies to
+             * avoid interference. */
+            int pitch = 1000;
+            
+            /* 4th harmonic falls in the FM frequency range */
+            int if_freq = 4 * mpeg_get_mas_pllfreq();
+
+            /* shift the mas harmonic >= 300 kHz away using the direction
+             * which needs less shifting. */
+            if (value < if_freq)
+            {
+                if (if_freq - value < 300000)
+                    pitch = 1003 - (if_freq - value) / 100000;
+            }
+            else
+            {
+                if (value - if_freq < 300000)
+                    pitch = 997 + (value - if_freq) / 100000;
+            }
+            sound_set_pitch(pitch);
+#endif
             /* We add the standard Intermediate Frequency 10.7MHz
             ** before calculating the divisor
             ** The reference frequency is set to 50kHz, and the VCO