linux-kernel - Re: meson-aiu: HDMI codec .prepare() callback not called

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Message-ID: <CAFBinCBLPFPotAzf_5Pdk1we9ygZdMagOEfnNBKWuCm-20iYHw@mail.gmail.com>
Date: Mon, 6 Jan 2025 15:15:32 +0100
From: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To: Jerome Brunet <jbrunet@...libre.com>
Cc: linux-amlogic@...ts.infradead.org, linux-sound@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	dmitry.baryshkov@...aro.org
Subject: Re: meson-aiu: HDMI codec .prepare() callback not called

On Mon, Jan 6, 2025 at 2:38 PM Martin Blumenstingl
<martin.blumenstingl@...glemail.com> wrote:
>
> Hi Jerome,
>
> On Mon, Jan 6, 2025 at 2:24 PM Jerome Brunet <jbrunet@...libre.com> wrote:
> >
> > On Mon 06 Jan 2025 at 13:49, Martin Blumenstingl <martin.blumenstingl@...glemail.com> wrote:
> >
> > > Hi Jerome,
> > >
> > > On Mon, Jan 6, 2025 at 11:44 AM Jerome Brunet <jbrunet@...libre.com> wrote:
> > > [...]
> > >> > I have further verified that the gx-card parsing does find the HDMi
> > >> > controller and links it correctly.
> > >> > To me it's odd that only the .prepare() callback is not called, all
> > >> > others (as mentioned above: .hw_params, .startup, ...) are working
> > >> > fine.
> > >>
> > >> I think the problem you are seeing comes from the quirk of
> > >> codec-to-codec links. The hdmi codec link is such a link on Amlogic
> > >> because further digital routing is required after the backend.
> > >>
> > >> Those type of links are not used much beside some
> > >> CPU offloading on Samsung and Amlogic, as far as I know.
> > >> It is possible, even likely, that things are still missing there.
> > >>
> > >> So those C2C links are operated by the DAPM events, not the regualar
> > >> ASoC code. You can start here:
> > >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/sound/soc/soc-dapm.c#n3995
> > > Thank you - that is indeed the root cause!
> > >
> > >> You'll see that .prepare() is not called, same as .trigger()
> > >> That should propably be fixed :/
> > > Since I'm still very much clueless about all of this I just came up
> > > with an experimental patch. Any feedback on it is welcome (I can send
> > > it as RFC patch - but prepare for me needing support).
> >
> > It is probably a good idea to send it to get more feedback, yes.
> Sure, I'll do that later and keep you Cc'ed.
patches are sent (with your feedback applied), let's continue in [0]


[0] https://lore.kernel.org/linux-sound/20250106141316.375984-1-martin.blumenstingl@googlemail.com/