code: plan9front

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aux/wm8960: fix chopped audio on the speakers with high volume

Jack detect becomes extremely unstable when playing on spk and the
volume is very high - DAC start to switch back and forth between two
outputs.  Solve this by always attenuating by -6dB and somewhat
limiting the volume on DAC ("master") - to 0xf9 instead of 0xff (max).

Also fix wrong output status reporting and remove "same volume - ignore"
optimization in setvol.

--- a/sys/src/cmd/aux/wm8960.c

+++ b/sys/src/cmd/aux/wm8960.c

@@ -65,11 +65,12 @@

 	wr(0x1a, reg1a);

 	if(o->toggle != nil)

 		o->toggle(o, on);

+	o->on = on;

 }

 static Out out[Nout] =

 {

-	[Dac] = {"master", 0x0a, 0xff, 3<<7, nil, 0},

+	[Dac] = {"master", 0x0a, 0xf9, 3<<7, nil, 0},

 	[Hp] = {"hp", 0x02, 0x7f, 3<<5, nil, 0},

 	[Spk] = {"spk", 0x28, 0x7f, 3<<3, classdspk, 0},

 };

@@ -79,13 +80,11 @@

 {

 	int zc;

-	l = CLAMP(l, 0, 100);

-	r = CLAMP(r, 0, 100);

-	if(l == o->vol[0] && r == o->vol[1])

-		return;

-	if((o->vol[0] = l) > 0)

+	o->vol[0] = l = CLAMP(l, 0, 100);

+	o->vol[1] = r = CLAMP(r, 0, 100);

+	if(l > 0)

 		l += o->volmax - 100;

-	if((o->vol[1] = r) > 0)

+	if(r > 0)

 		r += o->volmax - 100;

 	zc = o->volmax < 0x80;

@@ -161,6 +160,13 @@

 static void

 reset(void)

 {

+	int i;

+

+	for(i = 0; i < Nout; i++){

+		out[i].vol[0] = -1;

+		out[i].vol[1] = -1;

+	}

+

 	toggle(out+Dac, 0);

 	wr(0x1c, 1<<7 | 1<<4 | 1<<3 | 1<<2); /* Vmid/r bias; Vgs/r on; Vmid soft start */

 	wr(0x19, 0<<7); /* Vmid off, Vref off */

@@ -172,7 +178,7 @@

 	wr(0x07, 1<<6 | 2); /* master mode; i²s, 16-bit words */

-	wr(0x17, 1<<8 | 3<<6 | 1<<1); /* thermal shutdown on; avdd=3.3v; slow clock on */

+	wr(0x17, 1<<8 | 3<<6 | 0<<1); /* thermal shutdown on; avdd=3.3v; slow clock on */

 	wr(0x06, 1<<3 | 1<<2); /* ramp up DAC volume slowly */

 	wr(0x2f, 3<<2); /* output mixer on */

@@ -186,7 +192,11 @@

 	wr(0x1c, 1<<3); /* done with anti-pop */

 	wr(0x19, 1<<7 | 1<<6); /* Vref on */

-	wr(0x30, 2<<4 | 2<<2 | 1<<1); /* JD2 jack detect; Tsense on */

+	/*

+	 * Debounced jack detect output on gpio - no that it is used, but it

+	 * could be soldered to SoC's input and actually become useful.

+	 */

+	wr(0x30, 3<<4 | 2<<2 | 1<<1); /* JD2 jack detect in; Tsense on */

 	wr(0x1b, 1<<3); /* HP_[LR] responsive to jack detect */

 	wr(0x18, 1<<6); /* HP switch on; high = HP */

@@ -196,10 +206,17 @@

 	toggle(out+Dac, 1);

 	/* sensible defaults */

-	setvol(out+Spk, 80, 80);

-	setvol(out+Hp, 65, 65);

+	setvol(out+Spk, 100, 100);

+	setvol(out+Hp, 75, 75);

 	setvol(out+Dac, 80, 80);

-	wr(0x05, 0<<3); /* unmute DAC */

+

+	/*

+	 * Jack detect becomes extremely unstable when playing on spk and the

+	 * volume is very high - DAC start to switch back and forth between two

+	 * outputs.  Solve this by always attenuating by -6dB and somewhat limiting

+	 * the volume on DAC ("master") - to 0xf9 instead of 0xff (max).

+	 */

+	wr(0x05, 1<<7 | 0<<3); /* unmute DAC */

 }

 static void