ASoC: qcom: Limit Digital gains on speaker

Merge series from srinivas.kandagatla@linaro.org:

Limit the speaker digital gains to 0dB so that the users will not damage them.
Currently there is a limit in UCM, but this does not stop the user form
changing the digital gains from command line. So limit this in driver
which makes the speakers more safer without active speaker protection in
place.

Apart from this there is also a range check fix in snd_soc_limit_volume
to allow setting this limit correctly.

Tested on Lenovo X13s.

sound/soc/qcom/sc8280xp.c

@@ -27,6 +27,23 @@ struct sc8280xp_snd_data {
 static int sc8280xp_snd_init(struct snd_soc_pcm_runtime *rtd)
 {
 	struct sc8280xp_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;
+
+	switch (cpu_dai->id) {
+	case WSA_CODEC_DMA_RX_0:
+	case WSA_CODEC_DMA_RX_1:
+		/*
+		 * set limit of 0dB on Digital Volume for Speakers,
+		 * this can prevent damage of speakers to some extent without
+		 * active speaker protection
+		 */
+		snd_soc_limit_volume(card, "WSA_RX0 Digital Volume", 84);
+		snd_soc_limit_volume(card, "WSA_RX1 Digital Volume", 84);
+		break;
+	default:
+		break;
+	}
 
 	return qcom_snd_wcd_jack_setup(rtd, &data->jack, &data->jack_setup);
 }

sound/soc/soc-ops.c

@@ -661,7 +661,7 @@ int snd_soc_limit_volume(struct snd_soc_card *card,
 	kctl = snd_soc_card_get_kcontrol(card, name);
 	if (kctl) {
 		struct soc_mixer_control *mc = (struct soc_mixer_control *)kctl->private_value;
-		if (max <= mc->max) {
+		if (max <= mc->max - mc->min) {
 			mc->platform_max = max;
 			ret = 0;
 		}