Rockbox open source high quality audio player as a Music Player Daemon
mpris
rockbox
mpd
libadwaita
audio
rust
zig
deno
m3k: don't use mixer controls for volume control
According to a forum user, there's an audible click when changing
the volume between -32 and -32.5 dB with some headphones. Fix this
by not (ab)using the DAC digital mixer for volume control.
The mixer only provides an extra -6 dB of hardware volume range,
so the only side effect is that software volume will now kick in
at -32 dB instead of -38 dB.
Change-Id: If24d9bc0058eff3c1a29aefb155a2e378522623c
+8
-14
+8
-14
firmware/drivers/audio/ak4376.c
+8
-14
firmware/drivers/audio/ak4376.c
···
83
83
ak4376_set_pdn_pin(1);
84
84
mdelay(1);
85
85
86
-
static const int init_config[] = {
86
+
static const uint8_t init_config[] = {
87
87
/* Ensure HPRHZ, HPLHZ are 0 */
88
88
AK4376_REG_OUTPUT_MODE, 0x00,
89
89
/* Mute all volume controls */
90
-
AK4376_REG_MIXER, 0x00,
90
+
AK4376_REG_MIXER, AK4376_MIX_LCH | (AK4376_MIX_RCH << 4),
91
91
AK4376_REG_LCH_VOLUME, 0x80,
92
92
AK4376_REG_RCH_VOLUME, 0x00,
93
93
AK4376_REG_AMP_VOLUME, 0x00,
···
150
150
return x - rem;
151
151
}
152
152
153
-
static void calc_volumes(int vol, int* mix, int* dig, int* sw)
153
+
static void calc_volumes(int vol, int* dig, int* sw)
154
154
{
155
-
/* Mixer can divide by 2, which gives an extra -6 dB adjustment */
156
-
if(vol < AK4376_DIG_VOLUME_MIN) {
157
-
*mix |= AK4376_MIX_HALF;
158
-
vol += 60;
159
-
}
160
-
155
+
/* Apply digital volume */
161
156
*dig = round_step_up(vol, AK4376_DIG_VOLUME_STEP);
162
157
*dig = MIN(*dig, AK4376_DIG_VOLUME_MAX);
163
158
*dig = MAX(*dig, AK4376_DIG_VOLUME_MIN);
···
186
181
void ak4376_set_volume(int vol_l, int vol_r)
187
182
{
188
183
int amp;
189
-
int mix_l = AK4376_MIX_LCH, dig_l, sw_l;
190
-
int mix_r = AK4376_MIX_RCH, dig_r, sw_r;
184
+
int dig_l, sw_l;
185
+
int dig_r, sw_r;
191
186
192
187
if(vol_l <= AK4376_MIN_VOLUME && vol_r <= AK4376_MIN_VOLUME) {
193
188
/* Special case for full mute */
···
202
197
amp = MAX(amp, AK4376_AMP_VOLUME_MIN);
203
198
204
199
/* Other controls are stereo */
205
-
calc_volumes(vol_l - amp, &mix_l, &dig_l, &sw_l);
206
-
calc_volumes(vol_r - amp, &mix_r, &dig_r, &sw_r);
200
+
calc_volumes(vol_l - amp, &dig_l, &sw_l);
201
+
calc_volumes(vol_r - amp, &dig_r, &sw_r);
207
202
}
208
203
209
-
ak4376_write(AK4376_REG_MIXER, (mix_l & 0xf) | ((mix_r & 0xf) << 4));
210
204
ak4376_write(AK4376_REG_LCH_VOLUME, dig_vol_to_hw(dig_l) | (1 << 7));
211
205
ak4376_write(AK4376_REG_RCH_VOLUME, dig_vol_to_hw(dig_r));
212
206
ak4376_write(AK4376_REG_AMP_VOLUME, amp_vol_to_hw(amp));