[PATCH] ASoC: qcom: x1e80100: limit speaker volumes

[Tobias Heider]

Limit the digital gain and PA volumes to a combined -3 dB in the machine
driver to reduce the risk of speaker damage until we have active speaker
protection in place (or higher safe levels have been established).

Based on commit c481016bb4f8 ("ASoC: qcom: sc8280xp: limit speaker
volumes") which addressed the same issue on the sc8280x SoC with some
minor changes as explained below.

The Digital Volume behaves identical to sc8280x, both use the same
lpass-wsa-macro.
For PA x1e80100 machines use wsa884x amplifiers which expose a linear
scale from -9 dB to 9 dB with a 1.5 dB step size giving us
0 dB = -9 dB + 6 * 1.5 dB.

On x1e80100 there are two different speaker topologies we need to handle:
  2-Speakers: SpkrLeft, Spkr Right
  4-Speakers: WooferLeft, WooferRight, TweeterLeft, TweeterRight

Signed-off-by: Tobias Heider <tobias.heider@xxxxxxxxxxxxx>
---
On x1e80100 laptops like the Lenovo T14s Gen 6 most of the audio
enablement work has landed upstream at this point meaning it works
out of the box on any Linux system.
One unresolved problem is that there isn't a solution for active
speaker protection yet and the current default seems to be unsafe.

With the current defaults it is trivial to crank up the volume to
a point where the T14s will hit what I believe is a hardware
protection that shuts down the speakers entirely until the next
reboot. I am worried that this means there is also a risk cause
permanent hardware damage with the default settings.

This patch adopts the same limits we currently use for sc8280x to
x1e80100. With this applied I can't trigger the same shutoff I
described above.
---
 sound/soc/qcom/x1e80100.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/sound/soc/qcom/x1e80100.c b/sound/soc/qcom/x1e80100.c
index a3f4785c4bbe62e7e027deb6d810e0a0275d81c2..94ed3ade0dafb489adef3474b71d9d2487ee3890 100644
--- a/sound/soc/qcom/x1e80100.c
+++ b/sound/soc/qcom/x1e80100.c
@@ -27,10 +27,27 @@ static int x1e80100_snd_init(struct snd_soc_pcm_runtime *rtd)
 {
 	struct x1e80100_snd_data *data = snd_soc_card_get_drvdata(rtd->card);
 	struct snd_soc_dai *cpu_dai = snd_soc_rtd_to_cpu(rtd, 0);
+	struct snd_soc_card *card = rtd->card;
 	struct snd_soc_jack *dp_jack = NULL;
 	int dp_pcm_id = 0;
 
 	switch (cpu_dai->id) {
+	case WSA_CODEC_DMA_RX_0:
+	case WSA_CODEC_DMA_RX_1:
+		/*
+		 * Set limit of -3 dB on Digital Volume and 0 dB on PA Volume
+		 * to reduce the risk of speaker damage until we have active
+		 * speaker protection in place.
+		 */
+		snd_soc_limit_volume(card, "WSA_RX0 Digital Volume", 81);
+		snd_soc_limit_volume(card, "WSA_RX1 Digital Volume", 81);
+		snd_soc_limit_volume(card, "SpkrLeft PA Volume", 6);
+		snd_soc_limit_volume(card, "SpkrRight PA Volume", 6);
+		snd_soc_limit_volume(card, "WooferLeft PA Volume", 6);
+		snd_soc_limit_volume(card, "TweeterLeft PA Volume", 6);
+		snd_soc_limit_volume(card, "WooferRight PA Volume", 6);
+		snd_soc_limit_volume(card, "TweeterRight PA Volume", 6);
+		break;
 	case DISPLAY_PORT_RX_0:
 		dp_pcm_id = 0;
 		dp_jack = &data->dp_jack[dp_pcm_id];

---
base-commit: b4e07588e743c989499ca24d49e752c074924a9a
change-id: 20260421-x1e80100-audio-limit-f6e75e0ad422

Best regards,
-- 
Tobias Heider <tobias.heider@xxxxxxxxxxxxx>