snd_uaudio(4): Fix config detection with defaults set.

Let the USB audio descriptor iteration detect configurations with more
channels and larger sample size, even when the following global sysctl
tunables are set to a lower value:

hw.usb.uaudio.default_channels hw.usb.uaudio.default_bits

This improves utility and is closer to the meaning of default.

Also, do not create duplicate sample rate entries.

MFC after:	2 weeks
Reviewed by:    christos
Differential Revision:	https://reviews.freebsd.org/D43679

1 files changed, 46 insertions, 22 deletions

diff --git a/sys/dev/sound/usb/uaudio.c b/sys/dev/sound/usb/uaudio.c
index b0bf815f7797..eb4b676d5e7d 100644
--- a/sys/dev/sound/usb/uaudio.c
+++ b/sys/dev/sound/usb/uaudio.c
@@ -94,7 +94,7 @@
 #include "feeder_if.h"
 
 static int uaudio_default_rate = 0;		/* use rate list */
-static int uaudio_default_bits = 32;
+static int uaudio_default_bits = 0;		/* use default sample size */
 static int uaudio_default_channels = 0;		/* use default */
 static int uaudio_buffer_ms = 4;
 static bool uaudio_handle_hid = true;
@@ -150,6 +150,7 @@ SYSCTL_INT(_hw_usb_uaudio, OID_AUTO, debug, CTLFLAG_RWTUN,
 #define	UAUDIO_NFRAMES		64	/* must be factor of 8 due HS-USB */
 #define	UAUDIO_NCHANBUFS	2	/* number of outstanding request */
 #define	UAUDIO_RECURSE_LIMIT	255	/* rounds */
+#define	UAUDIO_BITS_MAX		32	/* maximum sample size in bits */
 #define	UAUDIO_CHANNELS_MAX	MIN(64, AFMT_CHANNEL_MAX)
 #define	UAUDIO_MATRIX_MAX	8	/* channels */
 
@@ -2203,31 +2204,37 @@ uaudio_chan_fill_info(struct uaudio_softc *sc, struct usb_device *udev)
 	uint8_t bits = uaudio_default_bits;
 	uint8_t y;
 	uint8_t channels = uaudio_default_channels;
+	uint8_t channels_max;
 	uint8_t x;
 
 	bits -= (bits % 8);
-	if ((bits == 0) || (bits > 32)) {
+	if ((bits == 0) || (bits > UAUDIO_BITS_MAX)) {
 		/* set a valid value */
-		bits = 32;
+		bits = UAUDIO_BITS_MAX;
 	}
-	if (channels == 0) {
-		switch (usbd_get_speed(udev)) {
-		case USB_SPEED_LOW:
-		case USB_SPEED_FULL:
-			/*
-			 * Due to high bandwidth usage and problems
-			 * with HIGH-speed split transactions we
-			 * disable surround setups on FULL-speed USB
-			 * by default
-			 */
-			channels = 4;
-			break;
-		default:
-			channels = UAUDIO_CHANNELS_MAX;
-			break;
-		}
-	} else if (channels > UAUDIO_CHANNELS_MAX)
+
+	if (channels > UAUDIO_CHANNELS_MAX)
 		channels = UAUDIO_CHANNELS_MAX;
+	switch (usbd_get_speed(udev)) {
+	case USB_SPEED_LOW:
+	case USB_SPEED_FULL:
+		/*
+		 * Due to high bandwidth usage and problems
+		 * with HIGH-speed split transactions we
+		 * disable surround setups on FULL-speed USB
+		 * by default
+		 */
+		channels_max = 4;
+		/* more channels on request */
+		if (channels > channels_max)
+			channels_max = channels;
+		break;
+	default:
+		channels_max = UAUDIO_CHANNELS_MAX;
+		break;
+	}
+	if (channels == 0)
+		channels = channels_max;
 
 	if (sbuf_new(&sc->sc_sndstat, NULL, 4096, SBUF_AUTOEXTEND))
 		sc->sc_sndstat_valid = 1;
@@ -2241,9 +2248,26 @@ uaudio_chan_fill_info(struct uaudio_softc *sc, struct usb_device *udev)
 				uaudio_chan_fill_info_sub(sc, udev, rate, x, y);
 
 			/* try find a matching rate, if any */
-			for (z = 0; uaudio_rate_list[z]; z++)
-				uaudio_chan_fill_info_sub(sc, udev, uaudio_rate_list[z], x, y);
+			for (z = 0; uaudio_rate_list[z]; z++) {
+				if (uaudio_rate_list[z] != rate)
+					uaudio_chan_fill_info_sub(sc, udev,
+					    uaudio_rate_list[z], x, y);
+			}
+
+			/* after default value in first round, proceed with max bits */
+			if (y == bits)
+				y = UAUDIO_BITS_MAX + 8;
+			/* skip default value subsequently */
+			if (y == (bits + 8))
+				y -= 8;
 		}
+
+		/* after default value in first round, proceed with max channels */
+		if (x == channels)
+			x = channels_max + 1;
+		/* skip default value subsequently */
+		if (x == (channels + 1))
+			x--;
 	}
 	if (sc->sc_sndstat_valid)
 		sbuf_finish(&sc->sc_sndstat);