Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 2 Aug 2023 13:09:16 +0100
From:   Mark Brown <broonie@kernel.org>
To:     Shengjiu Wang <shengjiu.wang@gmail.com>
Cc:     Takashi Iwai <tiwai@suse.de>, Hans Verkuil <hverkuil@xs4all.nl>,
        Shengjiu Wang <shengjiu.wang@nxp.com>, sakari.ailus@iki.fi,
        tfiga@chromium.org, m.szyprowski@samsung.com, mchehab@kernel.org,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        Xiubo.Lee@gmail.com, festevam@gmail.com, nicoleotsuka@gmail.com,
        lgirdwood@gmail.com, perex@perex.cz, tiwai@suse.com,
        alsa-devel@alsa-project.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [RFC PATCH v2 0/7] Add audio support in v4l2 framework
Message-ID: <b7120871-325c-4db0-a785-854b51ab680f@sirena.org.uk>
References: <1690265540-25999-1-git-send-email-shengjiu.wang@nxp.com>
 <47d66c28-1eb2-07f5-d6f9-779d675aefe8@xs4all.nl>
 <87il9xu1ro.wl-tiwai@suse.de>
 <CAA+D8ANmBKMp_L2GS=Lp-saMQKja6L4E6No3yP-e=a5YQBD_jQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
        protocol="application/pgp-signature"; boundary="s7JwRvdQJYqkq6dD"
Content-Disposition: inline
In-Reply-To: <CAA+D8ANmBKMp_L2GS=Lp-saMQKja6L4E6No3yP-e=a5YQBD_jQ@mail.gmail.com>
Precedence: bulk


--s7JwRvdQJYqkq6dD
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Wed, Aug 02, 2023 at 08:02:29PM +0800, Shengjiu Wang wrote:
> On Wed, Aug 2, 2023 at 7:22=E2=80=AFPM Takashi Iwai <tiwai@suse.de> wrote:

> > Well, I personally don't mind to have some audio capability in v4l2
> > layer.  But, the only uncertain thing for now is whether this is a
> > must-have or not.

> Thanks,  I am also not sure about this.  I am also confused that why
> there is no m2m implementation for audio in the kernel.  Audio also
> has similar decoder encoder post-processing as video.

This is the thing where we've been trying to persuade people to work on
replacing DPCM with full componentisation for about a decade now but
nobody's had time other than Morimoto-san who's been chipping away at
making everything component based for a good chunk of that time.  One
trick is that we don't just want this to work for things that are memory
to memory, we also want things where there's a direct interconnect that
bypasses memory for off-SoC case.

> The reason why I select to extend v4l2 for such audio usage is that v4l2
> looks best for this audio m2m implementation.  v4l2 is designed for m2m
> usage.  if we need implement another 'route',  I don't think it can do be=
tter
> that v4l2.

> I appreciate that someone can share his ideas or doable solutions.
> And please don't ignore my request, ignore my patch.

There's a bunch of presentations Lars-Peter did at ELC some considerable
time ago about this.

--s7JwRvdQJYqkq6dD
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----

iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmTKR2sACgkQJNaLcl1U
h9DDTwf/Xps9jJnts1SAD46EJPtve2N9sezS1xZvZgz0pluqjz+vDEyh+ediLcCy
uoiOc/xZz8Odde64unpb8nKuJzfH8hwdn4JFEMc9capaRijhM9iYxSNlDK6p0wil
AX82WXjRdrxyPbNJQgqYehJTbcydxIbewfCqG0ryrG+NeiAPZwR/p1IrCVzBrCZ5
E5+J4oQCAB7li51EuyZuihiImeoDS8LMbPJ5ciHXbhnXyIZaw8AvxTEz9d9llUl8
36hbfxrM24rlJDE16kRco/zHvMkK38W6fubovlGudON8xDoUBFZIPP3SWa5TRy7n
j3xcxiC0N3R2xWsDWKC3p7rK6OoiYQ==
=0Tfg
-----END PGP SIGNATURE-----

--s7JwRvdQJYqkq6dD--