3 files changed, 89 insertions, 42 deletions

diff --git a/include/sound/control.h b/include/sound/control.h
index bd7246de58e7..a1f1152bc687 100644
--- a/include/sound/control.h
+++ b/include/sound/control.h
@@ -248,6 +248,9 @@ int snd_ctl_add_vmaster_hook(struct snd_kcontrol *kctl,
                              void *private_data);
 void snd_ctl_sync_vmaster(struct snd_kcontrol *kctl, bool hook_only);
 #define snd_ctl_sync_vmaster_hook(kctl) snd_ctl_sync_vmaster(kctl, true)
+int snd_ctl_apply_vmaster_slaves(struct snd_kcontrol *kctl,
+                                 int (*func)(struct snd_kcontrol *, void *),
+                                 void *arg);
 
 /*
  * Helper functions for jack-detection controls
diff --git a/sound/core/vmaster.c b/sound/core/vmaster.c
index 6c58e6f73a01..e43af18d4383 100644
--- a/sound/core/vmaster.c
+++ b/sound/core/vmaster.c
@@ -484,3 +484,34 @@ void snd_ctl_sync_vmaster(struct snd_kcontrol *kcontrol, bool hook_only)
                 master->hook(master->hook_private_data, master->val);
 }
 EXPORT_SYMBOL_GPL(snd_ctl_sync_vmaster);
+
+/**
+ * snd_ctl_apply_vmaster_slaves - Apply function to each vmaster slave
+ * @kctl: vmaster kctl element
+ * @func: function to apply
+ * @arg: optional function argument
+ *
+ * Apply the function @func to each slave kctl of the given vmaster kctl.
+ * Returns 0 if successful, or a negative error code.
+ */
+int snd_ctl_apply_vmaster_slaves(struct snd_kcontrol *kctl,
+                                 int (*func)(struct snd_kcontrol *, void *),
+                                 void *arg)
+{
+        struct link_master *master;
+        struct link_slave *slave;
+        int err;
+
+        master = snd_kcontrol_chip(kctl);
+        err = master_init(master);
+        if (err < 0)
+                return err;
+        list_for_each_entry(slave, &master->slaves, list) {
+                err = func(&slave->slave, arg);
+                if (err < 0)
+                        return err;
+        }
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(snd_ctl_apply_vmaster_slaves);
diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index b6cf9684c2ec..a0989d231fd0 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -1803,36 +1803,6 @@ static int check_slave_present(struct hda_codec *codec,
         return 1;
 }
 
-/* guess the value corresponding to 0dB */
-static int get_kctl_0dB_offset(struct hda_codec *codec,
-                               struct snd_kcontrol *kctl, int *step_to_check)
-{
-        int _tlv[4];
-        const int *tlv = NULL;
-        int val = -1;
-
-        if ((kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) &&
-            kctl->tlv.c == snd_hda_mixer_amp_tlv) {
-                get_ctl_amp_tlv(kctl, _tlv);
-                tlv = _tlv;
-        } else if (kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_TLV_READ)
-                tlv = kctl->tlv.p;
-        if (tlv && tlv[0] == SNDRV_CTL_TLVT_DB_SCALE) {
-                int step = tlv[3];
-                step &= ~TLV_DB_SCALE_MUTE;
-                if (!step)
-                        return -1;
-                if (*step_to_check && *step_to_check != step) {
-                        codec_err(codec, "Mismatching dB step for vmaster slave (%d!=%d)\n",
-                                   *step_to_check, step);
-                        return -1;
-                }
-                *step_to_check = step;
-                val = -tlv[2] / step;
-        }
-        return val;
-}
-
 /* call kctl->put with the given value(s) */
 static int put_kctl_with_value(struct snd_kcontrol *kctl, int val)
 {
@@ -1847,19 +1817,58 @@ static int put_kctl_with_value(struct snd_kcontrol *kctl, int val)
         return 0;
 }
 
-/* initialize the slave volume with 0dB */
-static int init_slave_0dB(struct hda_codec *codec,
-                          void *data, struct snd_kcontrol *slave)
+struct slave_init_arg {
+        struct hda_codec *codec;
+        int step;
+};
+
+/* initialize the slave volume with 0dB via snd_ctl_apply_vmaster_slaves() */
+static int init_slave_0dB(struct snd_kcontrol *kctl, void *_arg)
 {
-        int offset = get_kctl_0dB_offset(codec, slave, data);
-        if (offset > 0)
-                put_kctl_with_value(slave, offset);
+        struct slave_init_arg *arg = _arg;
+        int _tlv[4];
+        const int *tlv = NULL;
+        int step;
+        int val;
+
+        if (kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {
+                if (kctl->tlv.c != snd_hda_mixer_amp_tlv) {
+                        codec_err(arg->codec,
+                                  "Unexpected TLV callback for slave %s:%d\n",
+                                  kctl->id.name, kctl->id.index);
+                        return 0; /* ignore */
+                }
+                get_ctl_amp_tlv(kctl, _tlv);
+                tlv = _tlv;
+        } else if (kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_TLV_READ)
+                tlv = kctl->tlv.p;
+
+        if (!tlv || tlv[0] != SNDRV_CTL_TLVT_DB_SCALE)
+                return 0;
+
+        step = tlv[3];
+        step &= ~TLV_DB_SCALE_MUTE;
+        if (!step)
+                return 0;
+        if (arg->step && arg->step != step) {
+                codec_err(arg->codec,
+                          "Mismatching dB step for vmaster slave (%d!=%d)\n",
+                          arg->step, step);
+                return 0;
+        }
+
+        arg->step = step;
+        val = -tlv[2] / step;
+        if (val > 0) {
+                put_kctl_with_value(kctl, val);
+                return val;
+        }
+
         return 0;
 }
 
-/* unmute the slave */
-static int init_slave_unmute(struct hda_codec *codec,
-                             void *data, struct snd_kcontrol *slave)
+/* unmute the slave via snd_ctl_apply_vmaster_slaves() */
+static int init_slave_unmute(struct snd_kcontrol *slave, void *_arg)
 {
         return put_kctl_with_value(slave, 1);
 }
@@ -1919,9 +1928,13 @@ int __snd_hda_add_vmaster(struct hda_codec *codec, char *name,
         /* init with master mute & zero volume */
         put_kctl_with_value(kctl, 0);
         if (init_slave_vol) {
-                int step = 0;
-                map_slaves(codec, slaves, suffix,
-                           tlv ? init_slave_0dB : init_slave_unmute, &step);
+                struct slave_init_arg arg = {
+                        .codec = codec,
+                        .step = 0,
+                };
+                snd_ctl_apply_vmaster_slaves(kctl,
+                                             tlv ? init_slave_0dB : init_slave_unmute,
+                                             &arg);
         }
 
         if (ctl_ret)