ASoC: adau17x1: Do not reload dsp-fw if samplerate has not changed

Reloading fw causes an audiable popping sound, we can avoid this
by not reloading if the samplerate is the same as before.
Signed-off-by: Danny Smith <dannys@axis.com>
Signed-off-by: Robert Rosengren <robert.rosengren@axis.com>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/adau17x1.c

@@ -843,6 +843,15 @@ int adau17x1_setup_firmware(struct snd_soc_component *component,
 	struct adau *adau = snd_soc_component_get_drvdata(component);
 	struct snd_soc_dapm_context *dapm = snd_soc_component_get_dapm(component);
 
+	/* Check if sample rate is the same as before. If it is there is no
+	 * point in performing the below steps as the call to
+	 * sigmadsp_setup(...) will return directly when it finds the sample
+	 * rate to be the same as before. By checking this we can prevent an
+	 * audiable popping noise which occours when toggling DSP_RUN.
+	 */
+	if (adau->sigmadsp->current_samplerate == rate)
+		return 0;
+
 	snd_soc_dapm_mutex_lock(dapm);
 
 	ret = regmap_read(adau->regmap, ADAU17X1_DSP_SAMPLING_RATE, &dspsr);