The put() callback of "IEC958 Playback Default" stores all 24 channel
status bytes and then returns 0. The core notifies userspace only on a
positive return, so a write that changes what the get() callback hands
back is never announced, and a mixer holding the control open keeps
showing the old value.

Compare the stored bytes and return 1 when they move, the way
snd_hda_spdif_default_put() does.

The same shape is in img-spdif-out and uniperif_player.

No board with this codec was to hand. The change is a comparison of
driver state with no hardware behaviour in it, and mixer-test counts the
missing notification as event_missing.

Fixes: 7a8e1d44211e ("ASoC: hdmi-codec: Add iec958 controls")
Signed-off-by: HyeongJun An <sammiee5311@gmail.com>
Assisted-by: Claude:claude-opus-5
---
 sound/soc/codecs/hdmi-codec.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/sound/soc/codecs/hdmi-codec.c b/sound/soc/codecs/hdmi-codec.c
index bc2c22436ba6..7aa50c5bd3df 100644
--- a/sound/soc/codecs/hdmi-codec.c
+++ b/sound/soc/codecs/hdmi-codec.c
@@ -426,10 +426,14 @@ static int hdmi_codec_iec958_default_put(struct snd_kcontrol *kcontrol,
 	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
 	struct hdmi_codec_priv *hcp = snd_soc_component_get_drvdata(component);
 
+	if (!memcmp(hcp->iec_status, ucontrol->value.iec958.status,
+		    sizeof(hcp->iec_status)))
+		return 0;
+
 	memcpy(hcp->iec_status, ucontrol->value.iec958.status,
 	       sizeof(hcp->iec_status));
 
-	return 0;
+	return 1;
 }
 
 static int hdmi_codec_iec958_mask_get(struct snd_kcontrol *kcontrol,
-- 
2.43.0

On Tue, 15 Sep 2026 18:25:15 +0900, HyeongJun An wrote:
> ASoC: hdmi-codec: Report a change when the channel status moves

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-7.3

Thanks!

[1/1] ASoC: hdmi-codec: Report a change when the channel status moves
      https://git.kernel.org/broonie/sound/c/c17ae8c26eac

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

On Tue, 15 Sep 2026 18:25:15 +0900, HyeongJun An wrote:
> ASoC: hdmi-codec: Report a change when the channel status moves

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-7.3

Thanks!

[1/1] ASoC: hdmi-codec: Report a change when the channel status moves
      https://git.kernel.org/broonie/sound/c/7abfc3b5d513

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark