shithub: riscv

Info  •  Files  •  Log  •  Branches

reform/audio: use soft-mute to toggle DAC

Disabling DAC caused an audible pop and would stop the clock, causing
any program writing to /dev/audio to halt until DAC would be enabled
again. Use "digital soft mute" instead - no clock stopping, nor pops.

--- a/sys/src/cmd/reform/audio.c

+++ b/sys/src/cmd/reform/audio.c

@@ -50,6 +50,18 @@

 }

 static void

+dactoggle(Out *, int on)

+{

+	/*

+	 * 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 | (!on)<<3);

+}

+

+static void

 classdspk(Out *, int on)

 {

 	wr(0x31, (on ? 3 : 0)<<6 | 0x37); /* class D SPK out */

@@ -70,7 +82,7 @@

 static Out out[Nout] =

 {

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

+	[Dac] = {"master", 0x0a, 0xf9, 0, dactoggle, 0},

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

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

 };

@@ -198,6 +210,10 @@

 	/* turn on all outputs */

 	toggle(out+Hp, 1);

 	toggle(out+Spk, 1);

+

+	/* enable/unmute DAC */

+	reg1a |= 3<<7;

+	wr(0x1a, reg1a); 

 	toggle(out+Dac, 1);

 	/* sensible defaults */

@@ -204,14 +220,6 @@

 	setvol(out+Spk, 100, 100);

 	setvol(out+Hp, 75, 75);

 	setvol(out+Dac, 80, 80);

-

-	/*

-	 * 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