[meta-freescale] Audio glitch with SGTL5000

[Nikolay Dimitrov]

Hi guys,

I'm observing a specific issue with SGTL5000 - after I stop the audio
playback, after several seconds there's a single strong audio glitch
(thump, pulse). In my case the audio codec is directly connected to the
product speaker amps (without any attenuators) and the experience can
be hardly described as pleasant...

I traced this behavior to the Linux kernel DAPM (Dynamic Audio Power
Management), which turns off all the analog and digital circuitry after
there's no audio stream for several seconds.

It looks like DAPM is not designed to be switched off, so I had to do
some (brutal) surgery to quick-solve the issue. I still have the
following gut feelings:
1. If this is an widespread issue, others should have seen it already.
2. If not, than maybe I have issue with my device tree and/or kernel
config.

Some info about my setup - imx6d, kernel 3.10.17-1.0.0ga, yocto daisy,
direct ALSA playback. Here's an extract of my DT audio settings:

sound {
	compatible = "fsl,imx-audio-sgtl5000";
	model = "imx6-myboard-sgtl5000";
	ssi-controller = <&ssi1>;
	audio-codec = <&codec>;
	audio-routing =
		"MIC_IN", "Mic Jack",
		"Mic Jack", "Mic Bias",
		"Headphone Jack", "HP_OUT";
	mux-int-port = <1>;
	mux-ext-port = <3>;
};

&ssi1 {
	fsl,mode = "i2s-slave";
	status = "okay";
};

Please share if you have observed similar behavior on your boards.
Thanks in advance!

Kind regards,
Nikolay