[alsa-devel] Broken outmixer_event function in wm8400/wm8990/wm8991

Mark Brown broonie at kernel.org
Tue May 13 18:09:24 CEST 2014

On Tue, May 13, 2014 at 02:53:05PM +0100, Charles Keepax wrote:

> Yeah I think the intention was to avoid imposing limitations on
> the order you set the controls, as the error checking is only
> done when the power sequence runs so you can move through an
> invalid state as long as when things power up they are valid.

Practically speaking we already have ordering restrictions - in general
you need to do a teardown followed by a setup otherwise there's a good
chance of causing audible noise from the switching during the setup.
Like Lars says we do run the event immediately anyway since the register
update is buried in DAPM processing for exactly this reason, we're
trying to avoid introducing a sudden DC offset by switching to/from an
active output so we see if we can power things down before we touch
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