On Mon, Feb 27, 2023 at 05:19:38PM +0800, Chancel Liu wrote: > wm8524 should be unmuted while power up and muted while power down. > @@ -75,7 +75,7 @@ static int wm8524_startup(struct snd_pcm_substream *substream, > SNDRV_PCM_HW_PARAM_RATE, > &wm8524->rate_constraint); > > - gpiod_set_value_cansleep(wm8524->mute, 1); > + gpiod_set_value_cansleep(wm8524->mute, 0); > > return 0; > } I *think* the theory with these is that the device should be muted by default so that any noise during startup is minimised, and only unmuted when there's an actual audio stream, done in wm8524_mute_stream(). I am unclear why this default state is set up in startup(), or why we unmute in shutdown(). It could be that the startup thing is trying to work around some suspend/resume thing? In any case I'm not sure this helps, I think really we should just not be managing the GPIO in these functions at all and setting the default state to be muted when the GPIO is requested. With this change we'd move the unmute _mute_stream() does much earlier, meaning that any noise output by the SoC during startup will get played.
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