[src/trunk]: src/sys/dev/usb Weed out duplicate sample rates and add comment ...

[mlelstv <mlelstv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/de9022868f0c
branches:  trunk
changeset: 374442:de9022868f0c
user:      mlelstv <mlelstv%NetBSD.org@localhost>
date:      Sun Apr 23 06:13:35 2023 +0000

description:
Weed out duplicate sample rates and add comment about UAC2 clocks.

diffstat:

 sys/dev/usb/uaudio.c |  33 ++++++++++++++++++++++++++++-----
 1 files changed, 28 insertions(+), 5 deletions(-)

diffs (61 lines):

diff -r f18d5e4c87db -r de9022868f0c sys/dev/usb/uaudio.c
--- a/sys/dev/usb/uaudio.c      Sun Apr 23 02:01:33 2023 +0000
+++ b/sys/dev/usb/uaudio.c      Sun Apr 23 06:13:35 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uaudio.c,v 1.179 2023/04/16 19:26:20 mlelstv Exp $     */
+/*     $NetBSD: uaudio.c,v 1.180 2023/04/23 06:13:35 mlelstv Exp $     */
 
 /*
  * Copyright (c) 1999, 2012 The NetBSD Foundation, Inc.
@@ -37,7 +37,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uaudio.c,v 1.179 2023/04/16 19:26:20 mlelstv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uaudio.c,v 1.180 2023/04/23 06:13:35 mlelstv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_usb.h"
@@ -2479,9 +2479,20 @@ Static u_int
 uaudio_get_rates(struct uaudio_softc *sc, int mode, u_int *freqs, u_int len)
 {
        struct mixerctl *mc;
-       u_int n, freq, start, end, step;
-       int j, k, count;
-
+       u_int freq, start, end, step;
+       u_int i, n;
+       u_int k, count;
+       int j;
+
+       /*
+        * With UAC2 the sample rate isn't part of the data format,
+        * instead, you have separate clock sources that may be
+        * assigned to individual terminals (inputs, outputs).
+        *
+        * For audio(4) we only distinguish between input and output
+        * formats and collect the unique rates from all possible clock
+        * sources.
+        */
        n = 0;
        for (j = 0; j < sc->sc_nratectls; ++j) {
 
@@ -2499,6 +2510,18 @@ uaudio_get_rates(struct uaudio_softc *sc
                        end   = (u_int) mc->ranges[k].maxval;
                        step  = (u_int) mc->ranges[k].resval;
                        for (freq = start; freq <= end; freq += step) {
+                               /* remove duplicates */
+                               for (i = 0; i < n; ++i) {
+                                       if (freqs[i] == freq)
+                                               break;
+                               }
+                               if (i < n) {
+                                       if (step == 0)
+                                               break;
+                                       continue;
+                               }
+
+                               /* store or count */
                                if (len != 0) {
                                        if (n >= len)
                                                goto done;