From d257b0e8a97541238c8e5af5471ecd31eb9c288a Mon Sep 17 00:00:00 2001
From: nia <nia@NetBSD.org>
Date: Mon, 20 May 2024 22:21:45 +0000
Subject: [PATCH] aiomixer(1): Fix setting volume on sb(4) emulated in QEMU.

The driver does not return a "delta", assume it's 16.
---
 usr.bin/aiomixer/main.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/usr.bin/aiomixer/main.c b/usr.bin/aiomixer/main.c
index 90f7fe1ba38d..8db914561ca6 100644
--- a/usr.bin/aiomixer/main.c
+++ b/usr.bin/aiomixer/main.c
@@ -1,4 +1,4 @@
-/* $NetBSD: main.c,v 1.5 2023/06/29 19:06:54 nia Exp $ */
+/* $NetBSD: main.c,v 1.6 2024/05/20 22:21:45 nia Exp $ */
 /*-
  * Copyright (c) 2021 The NetBSD Foundation, Inc.
  * All rights reserved.
@@ -149,7 +149,12 @@ slide_control(struct aiomixer *aio,
 
 	switch (info->type) {
 	case AUDIO_MIXER_VALUE:
-		delta = right ? info->un.v.delta : -info->un.v.delta;
+		if (info->un.v.delta != 0) {
+			delta = right ? info->un.v.delta : -info->un.v.delta;
+		} else {
+			/* delta is 0 in qemu with sb(4) */
+			delta = right ? 16 : -16;
+		}
 		/*
 		 * work around strange problem where the level can be
 		 * increased but not decreased, seen with uaudio(4)