linux-kernel - Re: [alsa-devel][PATCH 1/4] ASoC: wm8960: codec mclk should be enabled early to avoid jack detect error

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Message-ID: <20150611162028.GT14071@sirena.org.uk>
Date:	Thu, 11 Jun 2015 17:20:28 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Zidan Wang <zidan.wang@...escale.com>
Cc:	lgirdwood@...il.com, perex@...ex.cz, tiwai@...e.de,
	ckeepax@...nsource.wolfsonmicro.com, lars@...afoo.de,
	patches@...nsource.wolfsonmicro.com, alsa-devel@...a-project.org,
	linux-kernel@...r.kernel.org
Subject: Re: [alsa-devel][PATCH 1/4] ASoC: wm8960: codec mclk should be
 enabled early to avoid jack detect error

On Thu, Jun 11, 2015 at 07:14:33PM +0800, Zidan Wang wrote:
> It will playback from speaker in the first 2 seconds, then switch to
> headphone. Steps to reproduce this issue:
> 1. plug out headphone and playback a wav.
> 2. stop playback and wait for at least 5 seconds, then
>    plug in headphone and playback a wav.

I'd really like to understand the logic behind this in more detail -
what is the actual problem here and how does this fix it?  You're moving
the clock management from the bias level setting to the stream startup
and teardown which doesn't seem directly related, if anything it seems
like it'd be making things worse since it reduces the proportion of the
time where the clock is enabled.  My guess is that the jack detection
needs MCLK enabling.

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