ALSA: hda: Notify IEC958 Default PCM switch state changes

The "IEC958 Default PCM Playback Switch" control is backed directly by
mout->share_spdif. The share-switch callbacks currently access that state
without serialization, and spdif_share_sw_put() always returns 0, so
normal userspace writes never emit the standard ALSA control value
notification.

snd_hda_multi_out_analog_open() may also clear mout->share_spdif when the
analog PCM capabilities and the SPDIF capabilities no longer intersect.
That fallback is still needed to avoid creating an impossible hw
constraint set, but it changes the mixer backing value without notifying
subscribers.

Protect the share-switch callbacks with spdif_mutex like the other SPDIF
control handlers, return the actual change value from spdif_share_sw_put(),
and notify the cached control when the open path forcibly disables
shared SPDIF mode after dropping spdif_mutex.

This keeps the existing auto-disable behavior while making switch state
changes visible to userspace.

Fixes: 9a08160bdbe3 ("[ALSA] hda-codec - Add "IEC958 Default PCM" switch")
Fixes: 022b466fc353 ("ALSA: hda - Avoid invalid formats and rates with shared SPDIF")
Suggested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260403-hda-spdif-share-notify-v3-1-4eb1356b0f17@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/hda/common/codec.c b/sound/hda/common/codec.c
index 09b1329bb8f351897a2fee67968cbe08ba3f3edf..5123df32ad89f5a134994f63fa54eb050392f44f 100644 (file)
--- a/sound/hda/common/codec.c
+++ b/sound/hda/common/codec.c
@@ -2529,7 +2529,10 @@ EXPORT_SYMBOL_GPL(snd_hda_spdif_ctls_assign);
 static int spdif_share_sw_get(struct snd_kcontrol *kcontrol,
                              struct snd_ctl_elem_value *ucontrol)
 {
-       struct hda_multi_out *mout = snd_kcontrol_chip(kcontrol);
+       struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+       struct hda_multi_out *mout = (void *)kcontrol->private_value;
+
+       guard(mutex)(&codec->spdif_mutex);
        ucontrol->value.integer.value[0] = mout->share_spdif;
        return 0;
 }
@@ -2537,9 +2540,15 @@ static int spdif_share_sw_get(struct snd_kcontrol *kcontrol,
 static int spdif_share_sw_put(struct snd_kcontrol *kcontrol,
                              struct snd_ctl_elem_value *ucontrol)
 {
-       struct hda_multi_out *mout = snd_kcontrol_chip(kcontrol);
-       mout->share_spdif = !!ucontrol->value.integer.value[0];
-       return 0;
+       struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+       struct hda_multi_out *mout = (void *)kcontrol->private_value;
+       bool val = !!ucontrol->value.integer.value[0];
+       int change;
+
+       guard(mutex)(&codec->spdif_mutex);
+       change = mout->share_spdif != val;
+       mout->share_spdif = val;
+       return change;
 }
 
 static const struct snd_kcontrol_new spdif_share_sw = {
@@ -2550,6 +2559,14 @@ static const struct snd_kcontrol_new spdif_share_sw = {
        .put = spdif_share_sw_put,
 };
 
+static void notify_spdif_share_sw(struct hda_codec *codec,
+                                 struct hda_multi_out *mout)
+{
+       if (mout->share_spdif_kctl)
+               snd_ctl_notify_one(codec->card, SNDRV_CTL_EVENT_MASK_VALUE,
+                                  mout->share_spdif_kctl, 0);
+}
+
 /**
  * snd_hda_create_spdif_share_sw - create Default PCM switch
  * @codec: the HDA codec
@@ -2559,15 +2576,24 @@ int snd_hda_create_spdif_share_sw(struct hda_codec *codec,
                                  struct hda_multi_out *mout)
 {
        struct snd_kcontrol *kctl;
+       int err;
 
        if (!mout->dig_out_nid)
                return 0;
 
-       kctl = snd_ctl_new1(&spdif_share_sw, mout);
+       kctl = snd_ctl_new1(&spdif_share_sw, codec);
        if (!kctl)
                return -ENOMEM;
-       /* ATTENTION: here mout is passed as private_data, instead of codec */
-       return snd_hda_ctl_add(codec, mout->dig_out_nid, kctl);
+       /* snd_ctl_new1() stores @codec in private_data; stash @mout in
+        * private_value for the share-switch callbacks and cache the
+        * assigned control for forced-disable notifications.
+        */
+       kctl->private_value = (unsigned long)mout;
+       err = snd_hda_ctl_add(codec, mout->dig_out_nid, kctl);
+       if (err < 0)
+               return err;
+       mout->share_spdif_kctl = kctl;
+       return 0;
 }
 EXPORT_SYMBOL_GPL(snd_hda_create_spdif_share_sw);
 
@@ -3701,6 +3727,8 @@ int snd_hda_multi_out_analog_open(struct hda_codec *codec,
                                  struct hda_pcm_stream *hinfo)
 {
        struct snd_pcm_runtime *runtime = substream->runtime;
+       bool notify_share_sw = false;
+
        runtime->hw.channels_max = mout->max_channels;
        if (mout->dig_out_nid) {
                if (!mout->analog_rates) {
@@ -3729,10 +3757,12 @@ int snd_hda_multi_out_analog_open(struct hda_codec *codec,
                                        hinfo->maxbps = mout->spdif_maxbps;
                        } else {
                                mout->share_spdif = 0;
-                               /* FIXME: need notify? */
+                               notify_share_sw = true;
                        }
                }
        }
+       if (notify_share_sw)
+               notify_spdif_share_sw(codec, mout);
        return snd_pcm_hw_constraint_step(substream->runtime, 0,
                                          SNDRV_PCM_HW_PARAM_CHANNELS, 2);
 }

diff --git a/sound/hda/common/hda_local.h b/sound/hda/common/hda_local.h
index ab423f1cef5492d9b6fca20a72c136c36d4c656b..98b2c4acebc2739acd4172f6a00f7fb60dd13ab9 100644 (file)
--- a/sound/hda/common/hda_local.h
+++ b/sound/hda/common/hda_local.h
@@ -221,6 +221,7 @@ struct hda_multi_out {
        unsigned int spdif_rates;
        unsigned int spdif_maxbps;
        u64 spdif_formats;
+       struct snd_kcontrol *share_spdif_kctl; /* cached shared SPDIF switch */
 };
 
 int snd_hda_create_spdif_share_sw(struct hda_codec *codec,