Make usbaudio work for a few more devices (e.g Griffin iMic, some soundblasters,
devices with mono-only input).  Also make 'speed' settings for /dev/volume in
Hz instead of percentage of the range, to be compatible with audio(3).

(I noticed that ‘ls -m’ said I was the last person to modify this directory; I'm not sure what exactly I did. —btdn)

Reference: /n/sources/patch/applied/usbaudio-imic
Date: Sat Feb  3 22:28:14 CET 2007
Signed-off-by: miller@hamnavoe.com

--- /sys/src/cmd/usb/audio/audiosub.c	Fri Dec  8 11:34:30 2006
+++ /sys/src/cmd/usb/audio/audiosub.c	Fri Dec  8 11:34:27 2006
@@ -8,8 +8,10 @@
 Namelist terminal_types[] = {
 	{	0x100, "USB Terminal, undefined type"},
 	{	0x101, "USB Streaming"},
+	{	0x201, "Microphone"},
 	{	0x301, "Speaker"},
 	{	0x603, "Line connector"},
+	{	0x605, "S/PDIF"},
 	{	0, nil }
 };
 
@@ -153,6 +155,9 @@
 					if (selectorid[u] >= 0)
 						fprint(2, "Second selector (%d, %d) on %s\n", selectorid[u], b[3], u?"record":"playback");
 					selectorid[u] = b[3];
+					controls[u][Selector_control].readable = 1;
+					controls[u][Selector_control].settable = 1;
+					controls[u][Selector_control].chans = 0;
 				}
 			}
 			break;
--- /sys/src/cmd/usb/audio/usbaudioctl.c	Fri Dec  8 11:34:46 2006
+++ /sys/src/cmd/usb/audio/usbaudioctl.c	Fri Dec  8 11:34:42 2006
@@ -197,24 +197,32 @@
 		buf[0] = speed;
 		buf[1] = speed >> 8;
 		buf[2] = speed >> 16;
-		if(setupcmd(ad->ep[0], RH2D|Rclass|Rendpt, SET_CUR, sampling_freq_control<<8, endpt[rec], buf, 3) < 0){
+		n = endpt[rec];
+		if (rec)
+			n |= 0x80;
+		if(setupcmd(ad->ep[0], RH2D|Rclass|Rendpt, SET_CUR, sampling_freq_control<<8, n, buf, 3) < 0){
 			fprint(2, "Error in setupcmd\n");
 			return Undef;
 		}
-		if (setupreq(ad->ep[0], RD2H|Rclass|Rendpt, GET_CUR, sampling_freq_control<<8, endpt[rec], 3) < 0){
+		if (setupreq(ad->ep[0], RD2H|Rclass|Rendpt, GET_CUR, sampling_freq_control<<8, n, 3) < 0){
 			fprint(2, "Error in setupreq\n");
 			return Undef;
 		}
 		n = setupreply(ad->ep[0], buf, 3);
 		if (n != 3)
 			fprint(2, "Error in setupreply: %d\n", n);
-		else if (buf[2]){
-			if (debug & Dbgcontrol)
-				fprint(2, "Speed out of bounds %d (0x%x)\n",
-					buf[0] | buf[1] << 8 | buf[2] << 16,
-					buf[0] | buf[1] << 8 | buf[2] << 16);
-		}else
-			speed = buf[0] | buf[1] << 8 | buf[2] << 16;
+		else{
+			n = buf[0] | buf[1] << 8 | buf[2] << 16;
+			if (buf[2] || n == 0){
+				if (debug & Dbgcontrol)
+					fprint(2, "Speed out of bounds %d (0x%x)\n", n, n);
+			}else if (n != speed && ad->vid == 0x077d && (ad->did == 0x0223 || ad->did == 0x07af)){
+				/* Griffin iMic responds incorrectly to sample rate inquiry */
+				if (debug & Dbgcontrol)
+					fprint(2, " reported as %d (iMic bug?);", n);
+			}else
+				speed = n;
+		}
 		if (debug & Dbgcontrol)
 			fprint(2, " speed now %d Hz;", speed);
 	}
@@ -256,7 +264,7 @@
 	if (endpt[rec] < 0)
 		sysfatal("endpt[%s] not set\n", rec?"Record":"Playback");
 	if(debug & Dbgcontrol)
-		fprint(2, "getspeed: curalt[%d] == %d\n", rec, endpt[rec]);
+		fprint(2, "getspeed: endpt[%d] == %d\n", rec, endpt[rec]);
 	ep = ad->ep[endpt[rec]];
 	if (ep->iface == nil)
 		sysfatal("no interface");
@@ -274,7 +282,10 @@
 	if (a->caps & has_setspeed){
 		if(debug & Dbgcontrol)
 			fprint(2, "getspeed: has_setspeed, ask\n");
-		if (setupreq(ad->ep[0], RD2H|Rclass|Rendpt, which, sampling_freq_control<<8, endpt[rec], 3) < 0)
+		n = endpt[rec];
+		if (rec)
+			n |= 0x80;
+		if (setupreq(ad->ep[0], RD2H|Rclass|Rendpt, which, sampling_freq_control<<8, n, 3) < 0)
 			return Undef;
 		n = setupreply(ad->ep[0], buf, 3);
 		if(n == 3){
@@ -411,8 +422,8 @@
 		break;
 	case Selector_control:
 		type = RH2D|Rclass|Rinterface;
-		control = ctl<<8;
-		index = selectorid[rec];
+		control = 0;
+		index = selectorid[rec]<<8;
 		break;
 	case Channel_control:
 		control = findalt(rec, value[0], controls[rec][Resolution_control].value[0], defaultspeed[rec]);
@@ -463,10 +474,11 @@
 {
 	byte buf[3];
 	int m, n, i;
-	int type, control, index, count;
+	int type, control, index, count, signedbyte;
 	short svalue;
 
 	count = 1;
+	signedbyte = 0;
 	switch(ctl){
 	default:
 		return Undef;
@@ -488,22 +500,29 @@
 	case Delay_control:
 		count = 2;
 		/* fall through */
-	case Mute_control:
 	case Bass_control:
 	case Mid_control:
 	case Treble_control:
 	case Equalizer_control:
-	case Agc_control:
-	case Bassboost_control:
-	case Loudness_control:
+		signedbyte = 1;
 		type = RD2H|Rclass|Rinterface;
 		control = ctl<<8;
 		index = featureid[rec]<<8;
 		break;
 	case Selector_control:
 		type = RD2H|Rclass|Rinterface;
+		control = 0;
+		index = selectorid[rec]<<8;
+		break;
+	case Mute_control:
+	case Agc_control:
+	case Bassboost_control:
+	case Loudness_control:
+		if (req != GET_CUR)
+			return Undef;
+		type = RD2H|Rclass|Rinterface;
 		control = ctl<<8;
-		index = selectorid[rec];
+		index = featureid[rec]<<8;
 		break;
 	}
 	if (controls[rec][ctl].chans){
@@ -528,12 +547,15 @@
 						value[0] = svalue;
 					break;
 				case 1:
+					svalue = buf[0];
+					if (signedbyte && (svalue&0x80))
+						svalue |= 0xFF00;
 					if (req == GET_CUR){
-						value[i] = buf[0];
-						value[0] += buf[0];
+						value[i] = svalue;
+						value[0] += svalue;
 						m++;
 					}else
-						value[0] = buf[0];
+						value[0] = svalue;
 				}
 			}
 		}
@@ -552,7 +574,10 @@
 		value[0] = svalue;
 		break;
 	case 1:
-		value[0] = buf[0];
+		svalue = buf[0];
+		if (signedbyte && (svalue&0x80))
+			svalue |= 0xFF00;
+		value[0] = svalue;
 	}
 	return 0;
 }
--- /sys/src/cmd/usb/audio/audiofs.c	Fri Dec  8 11:35:04 2006
+++ /sys/src/cmd/usb/audio/audiofs.c	Fri Dec  8 11:35:00 2006
@@ -720,7 +720,7 @@
 				if (debug) fprint(2, "bad3\n");
 				return Ebadctl;
 			}
-			if (f->dir == &dirs[Qvolume] && c->min != Undef  && c->max != Undef){
+			if (f->dir == &dirs[Qvolume] && ctl != Speed_control && c->min != Undef && c->max != Undef){
 				nnf = tokenize(fields[nf-1], subfields, nelem(subfields));
 				if (nnf <= 0 || nnf > 8){
 					if (debug) fprint(2, "bad4\n");
--- /sys/src/cmd/usb/audio/usbaudio.c	Fri Dec  8 11:35:24 2006
+++ /sys/src/cmd/usb/audio/usbaudio.c	Fri Dec  8 11:35:20 2006
@@ -354,15 +354,22 @@
 	if (endpt[Record] >= 0){
 		if(verbose)
 			fprint(2, "Setting default record parameters: %d Hz, %d channels at %d bits\n",
-				defaultspeed[Play], 2, 16);
-		if(findalt(Record, 2, 16, defaultspeed[Record]) < 0){
-			if(findalt(Record, 2, 16, 48000) < 0)
+				defaultspeed[Record], 2, 16);
+		i = 2;
+		while(findalt(Record, i, 16, defaultspeed[Record]) < 0){
+			if(i == 2 && controls[Record][Channel_control].max == 1){
+				fprint(2, "Warning, can't configure stereo recording, configuring mono instead\n");
+				i = 1;
+				continue;
+			}
+			if(findalt(Record, i, 16, 48000) < 0)
 				sysfatal("Can't configure record for %d or %d Hz", defaultspeed[Record], 48000);
 			fprint(2, "Warning, can't configure record for %d Hz, configuring for %d Hz instead\n",
 				defaultspeed[Record], 48000);
 			defaultspeed[Record] = 48000;
+			break;
 		}
-		value[0] = 2;
+		value[0] = i;
 		if (setcontrol(Record, "channels", value) == Undef)
 			sysfatal("Can't set record channels\n");
 		value[0] = 16;
--- /sys/man/4/usb	Fri Dec  8 11:35:44 2006
+++ /sys/man/4/usb	Fri Dec  8 11:35:42 2006
@@ -108,7 +108,8 @@
 .PP
 This file can be written using the same syntax.  The keyword
 .I out
-may be omitted.  Settings are given as percentages of the range.
+may be omitted.  Settings are given as percentages of the range,
+except for speed which is in Hz.
 .PP
 The file
 .B audioctl