Hi Mark,
On Mon, Jun 06, 2022 at 05:44:41PM +0200, Lukasz Majewski wrote:
Without this change the BTL speaker produces some "distortion" noise when test program (speaker-test -t waw) is ended with ctrl+c.
As our design uses speaker outputs to drive BTL speaker, it was necessary to also mute the speaker via the codec internal WM8940_SPKVOL register with setting WM8940_SPKMUTE bit.
This will not interact well with both the user visible control of the speaker volume via the Speaker Playback Volume control and the analog bypass paths that the device has - it'll change the state of the control without generating any events, and cut off any bypassed audio that's mixed in.
I'm wondering why it is safe to call DAI's .digital_mute() callback, which explicitly changes state of the "DAC soft mute enable" bit (DACMU) ?
And on the other hand it is not correct to just mute the speakers?
You can probably achieve a similar effect by making the control an _AUTODISABLE one which will allow the core to mute the control when it's not being used in a way that's not visible to userspace.
The exact definition for the event, which I'm forcing above:
SOC_SINGLE("Speaker Playback Switch", WM8940_SPKVOL, 6, 1, 1),
And there is no SOC_SINGLE_AUTODISABLE() macro available.
The issue I'm trying to fix:
- The mclk clock is stopped (after some time) by imx SOC when I end 'speaker-test' program with ctrl+c.
- When the clock is not provided (after ~1sec) I do hear a single short noise from speakers.
- The other solution (which also works) would be to enable clock once (during probe) and then do not disable it till system is powered off (yes it is a hack :-) ).
I'm wondering if this can be fixed by some 'amixer' user space switch?
Thanks in advance for help.
Best regards,
Lukasz Majewski
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