linux-kernel - Re: [PATCH 3/4] ASoC: amd: acp: Add machine driver that enables sound for systems with a ES8336 codec

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Message-ID: <8cddbe1c-20d7-4b8f-ba02-f86bbb5a54c5@sirena.org.uk>
Date:   Fri, 18 Aug 2023 13:52:29 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Marian Postevca <posteuca@...ex.one>
Cc:     沈一超 <zhuning0077@...il.com>,
        yangxiaohua <yangxiaohua@...rest-semi.com>,
        Zhu Ning <zhuning@...rest-semi.com>,
        Takashi Iwai <tiwai@...e.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>, linux-kernel@...r.kernel.org,
        alsa-devel@...a-project.org
Subject: Re: [PATCH 3/4] ASoC: amd: acp: Add machine driver that enables
 sound for systems with a ES8336 codec

On Fri, Aug 18, 2023 at 01:20:06AM +0300, Marian Postevca wrote:
> Mark Brown <broonie@...nel.org> writes:

> > This is saying that the machine driver should disable jack detection
> > over suspend and restart it during resume.  The machine driver should
> > suspend before the rest of the card which should mean that the CODEC
> > gets powered off then.  The core can't tell if jack detection is
> > supposed to work over suspend, it is a standard wake event on systems
> > like phones, but it sounds like on this system the power gets removed
> > from the device so that can't work.

> Sorry, I don't understand what you are trying to say here. My intention
> is to find a way to have sound working when suspending/resuming
> with jack inserted by not fudging the jack in the machine driver but
> fixing it in the CODEC.

You'd need to pull the relevant supplies out of DAPM and handle them in
the CODEC suspend/resume callback.

> > I don't understand why that would be expected to help?  The main effect
> > of keeping the bias on all the time would be to consume more power.

> I don't fully understand the whole bias thing (I did try hard to
> understand it from the code), but in this specific instance it helps for
> suspending the CODEC. If idle_bias_on is true then idle_bias_off will be

Very old devices required keeping a reference voltage maintained at half
the analog supply voltage, this supply is called the bias.  It couldn't
be powered on/off quickly so needed to be kept on all the time.  I can't
tell which driver you're using here so I can't tell if it's maintaining
any system level power like that.

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