linux-kernel - Re: [PATCH v2 1/3] ASoC: hdmi-codec: Add event handler for hdmi TX

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Date:   Thu, 1 Dec 2022 15:06:04 +0000
From:   Jiaxin Yu (俞家鑫) <Jiaxin.Yu@...iatek.com>
To:     "broonie@...nel.org" <broonie@...nel.org>
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        Allen-KH Cheng (程冠勳) 
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Subject: Re: [PATCH v2 1/3] ASoC: hdmi-codec: Add event handler for hdmi TX

On Tue, 2022-11-29 at 17:22 +0000, Mark Brown wrote:
> On Mon, Nov 28, 2022 at 03:07:22PM +0000, Jiaxin Yu (俞家鑫) wrote:
> > On Fri, 2022-11-25 at 12:18 +0000, Mark Brown wrote:
> > > On Fri, Nov 25, 2022 at 05:44:11PM +0800, Jiaxin Yu wrote:
> > > I'm a little unclear why this is being implemented as a DAPM
> > > operation
> > > rather than having the driver forward the PCM trigger op if it's
> > > needed?
> > > Or alternatively if a DAPM callback is needed why not provide one
> > > directly rather than hooking into the trigger function - that's
> > > going
> > > to
> > > be called out of sequence with the rest of DAPM and be
> > > potentially
> > > confusing given the very different environments that trigger and
> > > DAPM
> > > operations run in.  A quick glance at the it6505 driver suggests
> > > it'd
> > > be
> > > happier with a DAPM callback.
> > Let me describe the hardware connection about mt8186 with
> > it6505(hdmi)
> > and rt1015p(speakers).
> >                        ==>it6505 
> >                      = 
> > DL1(FE) ==>I2S3(BE) =
> >                      =
> >                        ==>rt1015p
> > They shared the same one i2s port, but we'd like to control them
> > separately. So if hdmi-codec use the PCM trigger op, whne we turn
> > on
> > the speaker, hdmi-codec's PCM trigger op is also executed,
> > resulting in
> > sound on both devices.
> > Is there another way to control them separately? Thank you.
> 
> If you just need power control for one or both devices then the
> machine
> driver can add a _PIN_SWITCH() on the output of the device, that'll
> cause DAPM to keep the device powered down when not in use.  That
> should
> work well with the suggestion to provide a DAPM callback instead of a
> a
> trigger operation.

Yes, we do use a _PIN_SWITCH() on the outout of the device:

>  static const struct snd_kcontrol_new
>  mt8186_mt6366_rt1019_rt5682s_controls[] = {
>          SOC_DAPM_PIN_SWITCH("Speakers"),
>          SOC_DAPM_PIN_SWITCH("Headphone"),
>          SOC_DAPM_PIN_SWITCH("Headset Mic"),
>          SOC_DAPM_PIN_SWITCH("HDMI1"),
>  };

Which operation should I use to inform bridge driver to control audio
on or off? I'm curious why I don't see .trigger in the structure
hdmi_codec_ops compared to the structure snd_soc_dai_ops?