[alsa-devel] [PATCH] ASoC: rt5640: change widget sequence for depop

[Stephen Warren]

On 08/19/2013 06:18 AM, bardliao at realtek.com wrote:
> From: Bard Liao <bardliao at realtek.com>
> 
> Add mute/unmute control in widget event and modify the power on/off sequence to avoid pop noise.

This version breaks both headphone and speaker output. I see the
following issues:

1)

After a reboot, if all of "{HP,Speaker} [LR] Playback Switch" are
on/unmuted, and I start playback, then something sets all those controls
to off/muted. I suspect this is related to function rt5640_hp_event()
twiddling the same RT5640_[LR]_MUTE bits that the hp_[lr]_enable_control
controls twiddle.

2)

If playback is running, and (1) has caused all output to be muted, and I
then run alsamixer and enable/unmute "HP L Playback Switch", I hear
sound on both the L and R headphone channels for a very brief time, then
output switches to the L channel only. Similar happens if I unmute "HP R
Playback Switch" first. Unmuting both switches does produce stereo sound
as expected.

I don't know if this also happens for the speaker output, since the
board is too far away from me to easily tell which speakers are playing.