Speaker pops with max98357a on rk3399-gru-kevin since v5.7

[Tzung-Bi Shih]

On Thu, Jul 16, 2020 at 7:49 PM Alper Nebi Yasak
<alpernebiyasak at gmail.com> wrote:
> I have been getting "pop" sounds from the speaker on my rk3399-gru-kevin
> for a while, and bisected it to 128f825aeab7 ("ASoC: max98357a: move
> control of SD_MODE to DAPM"), but looks like the pops were somewhat
> expected:

I am not convinced the pop comes from 128f825aeab7.

> As of v5.8-rc5 I'm still getting the speaker pops. More info below, but
> not all pops coincide with "set sdmode" messages, and vice versa.
> Reverting that commit stops the pops, but then the "Speakers Switch" can
> no longer mute the speakers.

(I don't have a rk3399-gru-kevin so I got another test machine with MAX98357A.)
(I was testing with and without an audio server.)
Observations:
- I can hear the pop either with or without 128f825aeab7 (with and
without sdmode-delay).
- The pop noise is not always.  Higher probability after stopping
playback than before starting.
- As you also mentioned, the pop noise is not directly related to
SD_MODE transition.