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From: Shengjiu Wang <shengjiu.wang@gmail.com>
Date: Mon, 19 Feb 2024 14:35:53 +0800
Message-ID: <CAA+D8AM3mAbi-KQ14NOsnc5Rc1Z7kBYrtg56VwHjEiq5VNTc8A@mail.gmail.com>
Subject: Re: [PATCH v12 07/15] media: v4l2: Add audio capture and output support
To: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Shengjiu Wang <shengjiu.wang@nxp.com>, hverkuil@xs4all.nl, sakari.ailus@iki.fi, 
	tfiga@chromium.org, m.szyprowski@samsung.com, linux-media@vger.kernel.org, 
	linux-kernel@vger.kernel.org, Xiubo.Lee@gmail.com, festevam@gmail.com, 
	nicoleotsuka@gmail.com, lgirdwood@gmail.com, broonie@kernel.org, 
	perex@perex.cz, tiwai@suse.com, alsa-devel@alsa-project.org, 
	linuxppc-dev@lists.ozlabs.org
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Hi Mauro,  Hans

On Sat, Feb 17, 2024 at 5:42=E2=80=AFPM Mauro Carvalho Chehab
<mchehab@kernel.org> wrote:
>
> Em Thu, 18 Jan 2024 20:32:00 +0800
> Shengjiu Wang <shengjiu.wang@nxp.com> escreveu:
>
> > Audio signal processing has the requirement for memory to
> > memory similar as Video.
> >
> > This patch is to add this support in v4l2 framework, defined
> > new buffer type V4L2_BUF_TYPE_AUDIO_CAPTURE and
> > V4L2_BUF_TYPE_AUDIO_OUTPUT, defined new format v4l2_audio_format
> > for audio case usage.
> >
> > The created audio device is named "/dev/v4l-audioX".
> >
> > Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
> > ---
> >  .../userspace-api/media/v4l/buffer.rst        |  6 ++
> >  .../media/v4l/dev-audio-mem2mem.rst           | 71 +++++++++++++++++++
> >  .../userspace-api/media/v4l/devices.rst       |  1 +
> >  .../media/v4l/vidioc-enum-fmt.rst             |  2 +
> >  .../userspace-api/media/v4l/vidioc-g-fmt.rst  |  4 ++
> >  .../media/videodev2.h.rst.exceptions          |  2 +
> >  .../media/common/videobuf2/videobuf2-v4l2.c   |  4 ++
> >  drivers/media/v4l2-core/v4l2-compat-ioctl32.c |  9 +++
> >  drivers/media/v4l2-core/v4l2-dev.c            | 17 +++++
> >  drivers/media/v4l2-core/v4l2-ioctl.c          | 53 ++++++++++++++
> >  include/media/v4l2-dev.h                      |  2 +
> >  include/media/v4l2-ioctl.h                    | 34 +++++++++
> >  include/uapi/linux/videodev2.h                | 17 +++++
> >  13 files changed, 222 insertions(+)
> >  create mode 100644 Documentation/userspace-api/media/v4l/dev-audio-mem=
2mem.rst
> >
> > diff --git a/Documentation/userspace-api/media/v4l/buffer.rst b/Documen=
tation/userspace-api/media/v4l/buffer.rst
> > index 52bbee81c080..a3754ca6f0d6 100644
> > --- a/Documentation/userspace-api/media/v4l/buffer.rst
> > +++ b/Documentation/userspace-api/media/v4l/buffer.rst
> > @@ -438,6 +438,12 @@ enum v4l2_buf_type
> >      * - ``V4L2_BUF_TYPE_META_OUTPUT``
> >        - 14
>
> >        - Buffer for metadata output, see :ref:`metadata`.
> > +    * - ``V4L2_BUF_TYPE_AUDIO_CAPTURE``
> > +      - 15
> > +      - Buffer for audio capture, see :ref:`audio`.
> > +    * - ``V4L2_BUF_TYPE_AUDIO_OUTPUT``
> > +      - 16
>
> Hmm... alsa APi define input/output as:
>         enum {
>                 SNDRV_PCM_STREAM_PLAYBACK =3D 0,
>                 SNDRV_PCM_STREAM_CAPTURE,
>                 SNDRV_PCM_STREAM_LAST =3D SNDRV_PCM_STREAM_CAPTURE,
>         };
>
>
> I would use a namespace as close as possible to the
> ALSA API. Also, we're not talking about V4L2, but, instead
> audio. so, not sure if I like the prefix to start with
> V4L2_. Maybe ALSA_?
>
> So, a better namespace would be:
>
>         ${prefix}_BUF_TYPE_PCM_STREAM_PLAYBACK
> and
>         ${prefix}_BUF_TYPE_PCM_STREAM_CAPTURE
>

Ok,  So can I use the name below?
V4L2_BUF_TYPE_PCM_STREAM_PLAYBACK
V4L2_BUF_TYPE_PCM_STREAM_CAPTURE

> > +      - Buffer for audio output, see :ref:`audio`.
> >
> >
> >  .. _buffer-flags:
> > diff --git a/Documentation/userspace-api/media/v4l/dev-audio-mem2mem.rs=
t b/Documentation/userspace-api/media/v4l/dev-audio-mem2mem.rst
> > new file mode 100644
> > index 000000000000..68faecfe3a02
> > --- /dev/null
> > +++ b/Documentation/userspace-api/media/v4l/dev-audio-mem2mem.rst
> > @@ -0,0 +1,71 @@
> > +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
> > +
> > +.. _audiomem2mem:
> > +
> > +********************************
> > +Audio Memory-To-Memory Interface
> > +********************************
> > +
> > +An audio memory-to-memory device can compress, decompress, transform, =
or
> > +otherwise convert audio data from one format into another format, in m=
emory.
> > +Such memory-to-memory devices set the ``V4L2_CAP_AUDIO_M2M`` capabilit=
y.
> > +Examples of memory-to-memory devices are audio codecs, audio preproces=
sing,
> > +audio postprocessing.
> > +
> > +A memory-to-memory audio node supports both output (sending audio fram=
es from
> > +memory to the hardware) and capture (receiving the processed audio fra=
mes
> > +from the hardware into memory) stream I/O. An application will have to
> > +setup the stream I/O for both sides and finally call
> > +:ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>` for both capture and output t=
o
> > +start the hardware.
> > +
> > +Memory-to-memory devices function as a shared resource: you can
> > +open the audio node multiple times, each application setting up their
> > +own properties that are local to the file handle, and each can use
> > +it independently from the others. The driver will arbitrate access to
> > +the hardware and reprogram it whenever another file handler gets acces=
s.
> > +
> > +Audio memory-to-memory devices are accessed through character device
> > +special files named ``/dev/v4l-audio``
> > +
> > +Querying Capabilities
> > +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> > +
> > +Device nodes supporting the audio memory-to-memory interface set the
> > +``V4L2_CAP_AUDIO_M2M`` flag in the ``device_caps`` field of the
> > +:c:type:`v4l2_capability` structure returned by the :c:func:`VIDIOC_QU=
ERYCAP`
> > +ioctl.
> > +
> > +Data Format Negotiation
> > +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> > +
> > +The audio device uses the :ref:`format` ioctls to select the capture f=
ormat.
> > +The audio buffer content format is bound to that selected format. In a=
ddition
> > +to the basic :ref:`format` ioctls, the :c:func:`VIDIOC_ENUM_FMT` ioctl=
 must be
> > +supported as well.
> > +
> > +To use the :ref:`format` ioctls applications set the ``type`` field of=
 the
> > +:c:type:`v4l2_format` structure to ``V4L2_BUF_TYPE_AUDIO_CAPTURE`` or =
to
> > +``V4L2_BUF_TYPE_AUDIO_OUTPUT``. Both drivers and applications must set=
 the
> > +remainder of the :c:type:`v4l2_format` structure to 0.
> > +
> > +.. c:type:: v4l2_audio_format
> > +
> > +.. tabularcolumns:: |p{1.4cm}|p{2.4cm}|p{13.5cm}|
> > +
> > +.. flat-table:: struct v4l2_audio_format
> > +    :header-rows:  0
> > +    :stub-columns: 0
> > +    :widths:       1 1 2
> > +
> > +    * - __u32
> > +      - ``pixelformat``
> > +      - The sample format, set by the application. see :ref:`pixfmt-au=
dio`
>
> pixelformat doesn't make any sense for audio: there are no pixels on a
> PCM stream. Please use call it, instead: `snd_pcm_format`, making it matc=
h
> the values for snd_pcm_format_t.
>
> Yet, I would keep defining it as u32 (or u64?) instead of using a
> typedef int field there (snd_pcm_format_t), as the size of integer
> is different on 32 and 64 bit kernels.
>
>
> > +    * - __u32
> > +      - ``channels``
> > +      - The channel number, set by the application. channel number ran=
ge is
> > +        [1, 32].
>
> Why not start on zero?

channels in audio are at least 1.

>
> > +    * - __u32
> > +      - ``buffersize``
> > +      - Maximum buffer size in bytes required for data. The value is s=
et by the
> > +        driver.
> > diff --git a/Documentation/userspace-api/media/v4l/devices.rst b/Docume=
ntation/userspace-api/media/v4l/devices.rst
> > index 8bfbad65a9d4..758bd90f1c26 100644
> > --- a/Documentation/userspace-api/media/v4l/devices.rst
> > +++ b/Documentation/userspace-api/media/v4l/devices.rst
> > @@ -24,3 +24,4 @@ Interfaces
> >      dev-event
> >      dev-subdev
> >      dev-meta
> > +    dev-audio-mem2mem
> > diff --git a/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst =
b/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst
> > index 000c154b0f98..42deb07f4ff4 100644
> > --- a/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst
> > +++ b/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst
> > @@ -96,6 +96,8 @@ the ``mbus_code`` field is handled differently:
> >       ``V4L2_BUF_TYPE_VIDEO_OVERLAY``,
> >       ``V4L2_BUF_TYPE_SDR_CAPTURE``,
> >       ``V4L2_BUF_TYPE_SDR_OUTPUT``,
> > +     ``V4L2_BUF_TYPE_AUDIO_CAPTURE``,
> > +     ``V4L2_BUF_TYPE_AUDIO_OUTPUT``,
> >       ``V4L2_BUF_TYPE_META_CAPTURE`` and
> >       ``V4L2_BUF_TYPE_META_OUTPUT``.
> >       See :c:type:`v4l2_buf_type`.
> > diff --git a/Documentation/userspace-api/media/v4l/vidioc-g-fmt.rst b/D=
ocumentation/userspace-api/media/v4l/vidioc-g-fmt.rst
> > index 675c385e5aca..528fd9df41aa 100644
> > --- a/Documentation/userspace-api/media/v4l/vidioc-g-fmt.rst
> > +++ b/Documentation/userspace-api/media/v4l/vidioc-g-fmt.rst
> > @@ -130,6 +130,10 @@ The format as returned by :ref:`VIDIOC_TRY_FMT <VI=
DIOC_G_FMT>` must be identical
> >        - ``meta``
> >        - Definition of a metadata format, see :ref:`meta-formats`, used=
 by
> >       metadata capture devices.
> > +    * - struct :c:type:`v4l2_audio_format`
> > +      - ``audio``
> > +      - Definition of a audio data format, see :ref:`audiomem2mem`, us=
ed by
> > +        audio memory-to-memory devices
> >      * - __u8
> >        - ``raw_data``\ [200]
> >        - Place holder for future extensions.
> > diff --git a/Documentation/userspace-api/media/videodev2.h.rst.exceptio=
ns b/Documentation/userspace-api/media/videodev2.h.rst.exceptions
> > index da6d0b8e4c2c..e61152bb80d1 100644
> > --- a/Documentation/userspace-api/media/videodev2.h.rst.exceptions
> > +++ b/Documentation/userspace-api/media/videodev2.h.rst.exceptions
> > @@ -29,6 +29,8 @@ replace symbol V4L2_FIELD_SEQ_TB :c:type:`v4l2_field`
> >  replace symbol V4L2_FIELD_TOP :c:type:`v4l2_field`
> >
> >  # Documented enum v4l2_buf_type
> > +replace symbol V4L2_BUF_TYPE_AUDIO_CAPTURE :c:type:`v4l2_buf_type`
> > +replace symbol V4L2_BUF_TYPE_AUDIO_OUTPUT :c:type:`v4l2_buf_type`
> >  replace symbol V4L2_BUF_TYPE_META_CAPTURE :c:type:`v4l2_buf_type`
> >  replace symbol V4L2_BUF_TYPE_META_OUTPUT :c:type:`v4l2_buf_type`
> >  replace symbol V4L2_BUF_TYPE_SDR_CAPTURE :c:type:`v4l2_buf_type`
> > diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/=
media/common/videobuf2/videobuf2-v4l2.c
> > index 54d572c3b515..16ab204d15b0 100644
> > --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
> > +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> > @@ -791,6 +791,10 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4=
l2_create_buffers *create)
> >       case V4L2_BUF_TYPE_META_OUTPUT:
> >               requested_sizes[0] =3D f->fmt.meta.buffersize;
> >               break;
> > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
> > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
> > +             requested_sizes[0] =3D f->fmt.audio.buffersize;
> > +             break;
> >       default:
> >               return -EINVAL;
> >       }
> > diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/me=
dia/v4l2-core/v4l2-compat-ioctl32.c
> > index 8c07400bd280..5e94db8dfdae 100644
> > --- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
> > +++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
> > @@ -101,6 +101,7 @@ struct v4l2_format32 {
> >               struct v4l2_sliced_vbi_format   sliced;
> >               struct v4l2_sdr_format  sdr;
> >               struct v4l2_meta_format meta;
> > +             struct v4l2_audio_format        audio;
> >               __u8    raw_data[200];        /* user-defined */
> >       } fmt;
> >  };
> > @@ -166,6 +167,10 @@ static int get_v4l2_format32(struct v4l2_format *p=
64,
> >       case V4L2_BUF_TYPE_META_OUTPUT:
> >               return copy_from_user(&p64->fmt.meta, &p32->fmt.meta,
> >                                     sizeof(p64->fmt.meta)) ? -EFAULT : =
0;
> > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
> > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
> > +             return copy_from_user(&p64->fmt.audio, &p32->fmt.audio,
> > +                                   sizeof(p64->fmt.audio)) ? -EFAULT :=
 0;
> >       default:
> >               return -EINVAL;
> >       }
> > @@ -216,6 +221,10 @@ static int put_v4l2_format32(struct v4l2_format *p=
64,
> >       case V4L2_BUF_TYPE_META_OUTPUT:
> >               return copy_to_user(&p32->fmt.meta, &p64->fmt.meta,
> >                                   sizeof(p64->fmt.meta)) ? -EFAULT : 0;
> > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
> > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
> > +             return copy_to_user(&p32->fmt.audio, &p64->fmt.audio,
> > +                                 sizeof(p64->fmt.audio)) ? -EFAULT : 0=
;
> >       default:
> >               return -EINVAL;
> >       }
> > diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-co=
re/v4l2-dev.c
> > index d13954bd31fd..bac008fcedc6 100644
> > --- a/drivers/media/v4l2-core/v4l2-dev.c
> > +++ b/drivers/media/v4l2-core/v4l2-dev.c
> > @@ -553,6 +553,7 @@ static void determine_valid_ioctls(struct video_dev=
ice *vdev)
> >       bool is_tch =3D vdev->vfl_type =3D=3D VFL_TYPE_TOUCH;
> >       bool is_meta =3D vdev->vfl_type =3D=3D VFL_TYPE_VIDEO &&
> >                      (vdev->device_caps & meta_caps);
> > +     bool is_audio =3D vdev->vfl_type =3D=3D VFL_TYPE_AUDIO;
> >       bool is_rx =3D vdev->vfl_dir !=3D VFL_DIR_TX;
> >       bool is_tx =3D vdev->vfl_dir !=3D VFL_DIR_RX;
> >       bool is_io_mc =3D vdev->device_caps & V4L2_CAP_IO_MC;
> > @@ -666,6 +667,19 @@ static void determine_valid_ioctls(struct video_de=
vice *vdev)
> >               SET_VALID_IOCTL(ops, VIDIOC_S_FMT, vidioc_s_fmt_meta_out)=
;
> >               SET_VALID_IOCTL(ops, VIDIOC_TRY_FMT, vidioc_try_fmt_meta_=
out);
> >       }
> > +     if (is_audio && is_rx) {
> > +             /* audio capture specific ioctls */
> > +             SET_VALID_IOCTL(ops, VIDIOC_ENUM_FMT, vidioc_enum_fmt_aud=
io_cap);
> > +             SET_VALID_IOCTL(ops, VIDIOC_G_FMT, vidioc_g_fmt_audio_cap=
);
> > +             SET_VALID_IOCTL(ops, VIDIOC_S_FMT, vidioc_s_fmt_audio_cap=
);
> > +             SET_VALID_IOCTL(ops, VIDIOC_TRY_FMT, vidioc_try_fmt_audio=
_cap);
> > +     } else if (is_audio && is_tx) {
> > +             /* audio output specific ioctls */
> > +             SET_VALID_IOCTL(ops, VIDIOC_ENUM_FMT, vidioc_enum_fmt_aud=
io_out);
> > +             SET_VALID_IOCTL(ops, VIDIOC_G_FMT, vidioc_g_fmt_audio_out=
);
> > +             SET_VALID_IOCTL(ops, VIDIOC_S_FMT, vidioc_s_fmt_audio_out=
);
> > +             SET_VALID_IOCTL(ops, VIDIOC_TRY_FMT, vidioc_try_fmt_audio=
_out);
> > +     }
> >       if (is_vbi) {
> >               /* vbi specific ioctls */
> >               if ((is_rx && (ops->vidioc_g_fmt_vbi_cap ||
> > @@ -929,6 +943,9 @@ int __video_register_device(struct video_device *vd=
ev,
> >       case VFL_TYPE_TOUCH:
> >               name_base =3D "v4l-touch";
> >               break;
> > +     case VFL_TYPE_AUDIO:
> > +             name_base =3D "v4l-audio";
> > +             break;
> >       default:
> >               pr_err("%s called with unknown type: %d\n",
> >                      __func__, type);
> > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-=
core/v4l2-ioctl.c
> > index 33076af4dfdb..e7be7c2f302d 100644
> > --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> > @@ -188,6 +188,8 @@ const char *v4l2_type_names[] =3D {
> >       [V4L2_BUF_TYPE_SDR_OUTPUT]         =3D "sdr-out",
> >       [V4L2_BUF_TYPE_META_CAPTURE]       =3D "meta-cap",
> >       [V4L2_BUF_TYPE_META_OUTPUT]        =3D "meta-out",
> > +     [V4L2_BUF_TYPE_AUDIO_CAPTURE]      =3D "audio-cap",
> > +     [V4L2_BUF_TYPE_AUDIO_OUTPUT]       =3D "audio-out",
> >  };
> >  EXPORT_SYMBOL(v4l2_type_names);
> >
> > @@ -276,6 +278,7 @@ static void v4l_print_format(const void *arg, bool =
write_only)
> >       const struct v4l2_sliced_vbi_format *sliced;
> >       const struct v4l2_window *win;
> >       const struct v4l2_meta_format *meta;
> > +     const struct v4l2_audio_format *audio;
> >       u32 pixelformat;
> >       u32 planes;
> >       unsigned i;
> > @@ -346,6 +349,13 @@ static void v4l_print_format(const void *arg, bool=
 write_only)
> >               pr_cont(", dataformat=3D%p4cc, buffersize=3D%u\n",
> >                       &pixelformat, meta->buffersize);
> >               break;
> > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
> > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
> > +             audio =3D &p->fmt.audio;
> > +             pixelformat =3D audio->audioformat;
> > +             pr_cont(", format=3D%p4cc, channels=3D%u, buffersize=3D%u=
\n",
> > +                     &pixelformat, audio->channels, audio->buffersize)=
;
> > +             break;
> >       }
> >  }
> >
> > @@ -927,6 +937,7 @@ static int check_fmt(struct file *file, enum v4l2_b=
uf_type type)
> >       bool is_tch =3D vfd->vfl_type =3D=3D VFL_TYPE_TOUCH;
> >       bool is_meta =3D vfd->vfl_type =3D=3D VFL_TYPE_VIDEO &&
> >                      (vfd->device_caps & meta_caps);
> > +     bool is_audio =3D vfd->vfl_type =3D=3D VFL_TYPE_AUDIO;
> >       bool is_rx =3D vfd->vfl_dir !=3D VFL_DIR_TX;
> >       bool is_tx =3D vfd->vfl_dir !=3D VFL_DIR_RX;
> >
> > @@ -992,6 +1003,14 @@ static int check_fmt(struct file *file, enum v4l2=
_buf_type type)
> >               if (is_meta && is_tx && ops->vidioc_g_fmt_meta_out)
> >                       return 0;
> >               break;
> > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
> > +             if (is_audio && is_rx && ops->vidioc_g_fmt_audio_cap)
> > +                     return 0;
> > +             break;
> > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
> > +             if (is_audio && is_tx && ops->vidioc_g_fmt_audio_out)
> > +                     return 0;
> > +             break;
> >       default:
> >               break;
> >       }
> > @@ -1597,6 +1616,16 @@ static int v4l_enum_fmt(const struct v4l2_ioctl_=
ops *ops,
> >                       break;
> >               ret =3D ops->vidioc_enum_fmt_meta_out(file, fh, arg);
> >               break;
> > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
> > +             if (unlikely(!ops->vidioc_enum_fmt_audio_cap))
> > +                     break;
> > +             ret =3D ops->vidioc_enum_fmt_audio_cap(file, fh, arg);
> > +             break;
> > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
> > +             if (unlikely(!ops->vidioc_enum_fmt_audio_out))
> > +                     break;
> > +             ret =3D ops->vidioc_enum_fmt_audio_out(file, fh, arg);
> > +             break;
> >       }
> >       if (ret =3D=3D 0)
> >               v4l_fill_fmtdesc(p);
> > @@ -1673,6 +1702,10 @@ static int v4l_g_fmt(const struct v4l2_ioctl_ops=
 *ops,
> >               return ops->vidioc_g_fmt_meta_cap(file, fh, arg);
> >       case V4L2_BUF_TYPE_META_OUTPUT:
> >               return ops->vidioc_g_fmt_meta_out(file, fh, arg);
> > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
> > +             return ops->vidioc_g_fmt_audio_cap(file, fh, arg);
> > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
> > +             return ops->vidioc_g_fmt_audio_out(file, fh, arg);
> >       }
> >       return -EINVAL;
> >  }
> > @@ -1784,6 +1817,16 @@ static int v4l_s_fmt(const struct v4l2_ioctl_ops=
 *ops,
> >                       break;
> >               memset_after(p, 0, fmt.meta);
> >               return ops->vidioc_s_fmt_meta_out(file, fh, arg);
> > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
> > +             if (unlikely(!ops->vidioc_s_fmt_audio_cap))
> > +                     break;
> > +             memset_after(p, 0, fmt.audio);
> > +             return ops->vidioc_s_fmt_audio_cap(file, fh, arg);
> > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
> > +             if (unlikely(!ops->vidioc_s_fmt_audio_out))
> > +                     break;
> > +             memset_after(p, 0, fmt.audio);
> > +             return ops->vidioc_s_fmt_audio_out(file, fh, arg);
> >       }
> >       return -EINVAL;
> >  }
> > @@ -1892,6 +1935,16 @@ static int v4l_try_fmt(const struct v4l2_ioctl_o=
ps *ops,
> >                       break;
> >               memset_after(p, 0, fmt.meta);
> >               return ops->vidioc_try_fmt_meta_out(file, fh, arg);
> > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
> > +             if (unlikely(!ops->vidioc_try_fmt_audio_cap))
> > +                     break;
> > +             memset_after(p, 0, fmt.audio);
> > +             return ops->vidioc_try_fmt_audio_cap(file, fh, arg);
> > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
> > +             if (unlikely(!ops->vidioc_try_fmt_audio_out))
> > +                     break;
> > +             memset_after(p, 0, fmt.audio);
> > +             return ops->vidioc_try_fmt_audio_out(file, fh, arg);
> >       }
> >       return -EINVAL;
> >  }
> > diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
> > index d82dfdbf6e58..82b63f82d43f 100644
> > --- a/include/media/v4l2-dev.h
> > +++ b/include/media/v4l2-dev.h
> > @@ -30,6 +30,7 @@
> >   * @VFL_TYPE_SUBDEV: for V4L2 subdevices
> >   * @VFL_TYPE_SDR:    for Software Defined Radio tuners
> >   * @VFL_TYPE_TOUCH:  for touch sensors
> > + * @VFL_TYPE_AUDIO:  for audio memory-to-memory devices
> >   * @VFL_TYPE_MAX:    number of VFL types, must always be last in the e=
num
> >   */
> >  enum vfl_devnode_type {
> > @@ -39,6 +40,7 @@ enum vfl_devnode_type {
> >       VFL_TYPE_SUBDEV,
> >       VFL_TYPE_SDR,
> >       VFL_TYPE_TOUCH,
> > +     VFL_TYPE_AUDIO,
> >       VFL_TYPE_MAX /* Shall be the last one */
> >  };
> >
> > diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
> > index edb733f21604..f840cf740ce1 100644
> > --- a/include/media/v4l2-ioctl.h
> > +++ b/include/media/v4l2-ioctl.h
> > @@ -45,6 +45,12 @@ struct v4l2_fh;
> >   * @vidioc_enum_fmt_meta_out: pointer to the function that implements
> >   *   :ref:`VIDIOC_ENUM_FMT <vidioc_enum_fmt>` ioctl logic
> >   *   for metadata output
> > + * @vidioc_enum_fmt_audio_cap: pointer to the function that implements
> > + *   :ref:`VIDIOC_ENUM_FMT <vidioc_enum_fmt>` ioctl logic
> > + *   for audio capture
> > + * @vidioc_enum_fmt_audio_out: pointer to the function that implements
> > + *   :ref:`VIDIOC_ENUM_FMT <vidioc_enum_fmt>` ioctl logic
> > + *   for audio output
> >   * @vidioc_g_fmt_vid_cap: pointer to the function that implements
> >   *   :ref:`VIDIOC_G_FMT <vidioc_g_fmt>` ioctl logic for video capture
> >   *   in single plane mode
> > @@ -79,6 +85,10 @@ struct v4l2_fh;
> >   *   :ref:`VIDIOC_G_FMT <vidioc_g_fmt>` ioctl logic for metadata captu=
re
> >   * @vidioc_g_fmt_meta_out: pointer to the function that implements
> >   *   :ref:`VIDIOC_G_FMT <vidioc_g_fmt>` ioctl logic for metadata outpu=
t
> > + * @vidioc_g_fmt_audio_cap: pointer to the function that implements
> > + *   :ref:`VIDIOC_G_FMT <vidioc_g_fmt>` ioctl logic for audio capture
> > + * @vidioc_g_fmt_audio_out: pointer to the function that implements
> > + *   :ref:`VIDIOC_G_FMT <vidioc_g_fmt>` ioctl logic for audio output
> >   * @vidioc_s_fmt_vid_cap: pointer to the function that implements
> >   *   :ref:`VIDIOC_S_FMT <vidioc_g_fmt>` ioctl logic for video capture
> >   *   in single plane mode
> > @@ -113,6 +123,10 @@ struct v4l2_fh;
> >   *   :ref:`VIDIOC_S_FMT <vidioc_g_fmt>` ioctl logic for metadata captu=
re
> >   * @vidioc_s_fmt_meta_out: pointer to the function that implements
> >   *   :ref:`VIDIOC_S_FMT <vidioc_g_fmt>` ioctl logic for metadata outpu=
t
> > + * @vidioc_s_fmt_audio_cap: pointer to the function that implements
> > + *   :ref:`VIDIOC_S_FMT <vidioc_g_fmt>` ioctl logic for audio capture
> > + * @vidioc_s_fmt_audio_out: pointer to the function that implements
> > + *   :ref:`VIDIOC_S_FMT <vidioc_g_fmt>` ioctl logic for audio output
> >   * @vidioc_try_fmt_vid_cap: pointer to the function that implements
> >   *   :ref:`VIDIOC_TRY_FMT <vidioc_g_fmt>` ioctl logic for video captur=
e
> >   *   in single plane mode
> > @@ -149,6 +163,10 @@ struct v4l2_fh;
> >   *   :ref:`VIDIOC_TRY_FMT <vidioc_g_fmt>` ioctl logic for metadata cap=
ture
> >   * @vidioc_try_fmt_meta_out: pointer to the function that implements
> >   *   :ref:`VIDIOC_TRY_FMT <vidioc_g_fmt>` ioctl logic for metadata out=
put
> > + * @vidioc_try_fmt_audio_cap: pointer to the function that implements
> > + *   :ref:`VIDIOC_TRY_FMT <vidioc_g_fmt>` ioctl logic for audio captur=
e
> > + * @vidioc_try_fmt_audio_out: pointer to the function that implements
> > + *   :ref:`VIDIOC_TRY_FMT <vidioc_g_fmt>` ioctl logic for audio output
> >   * @vidioc_reqbufs: pointer to the function that implements
> >   *   :ref:`VIDIOC_REQBUFS <vidioc_reqbufs>` ioctl
> >   * @vidioc_querybuf: pointer to the function that implements
> > @@ -315,6 +333,10 @@ struct v4l2_ioctl_ops {
> >                                       struct v4l2_fmtdesc *f);
> >       int (*vidioc_enum_fmt_meta_out)(struct file *file, void *fh,
> >                                       struct v4l2_fmtdesc *f);
> > +     int (*vidioc_enum_fmt_audio_cap)(struct file *file, void *fh,
> > +                                      struct v4l2_fmtdesc *f);
> > +     int (*vidioc_enum_fmt_audio_out)(struct file *file, void *fh,
> > +                                      struct v4l2_fmtdesc *f);
> >
> >       /* VIDIOC_G_FMT handlers */
> >       int (*vidioc_g_fmt_vid_cap)(struct file *file, void *fh,
> > @@ -345,6 +367,10 @@ struct v4l2_ioctl_ops {
> >                                    struct v4l2_format *f);
> >       int (*vidioc_g_fmt_meta_out)(struct file *file, void *fh,
> >                                    struct v4l2_format *f);
> > +     int (*vidioc_g_fmt_audio_cap)(struct file *file, void *fh,
> > +                                   struct v4l2_format *f);
> > +     int (*vidioc_g_fmt_audio_out)(struct file *file, void *fh,
> > +                                   struct v4l2_format *f);
> >
> >       /* VIDIOC_S_FMT handlers */
> >       int (*vidioc_s_fmt_vid_cap)(struct file *file, void *fh,
> > @@ -375,6 +401,10 @@ struct v4l2_ioctl_ops {
> >                                    struct v4l2_format *f);
> >       int (*vidioc_s_fmt_meta_out)(struct file *file, void *fh,
> >                                    struct v4l2_format *f);
> > +     int (*vidioc_s_fmt_audio_cap)(struct file *file, void *fh,
> > +                                   struct v4l2_format *f);
> > +     int (*vidioc_s_fmt_audio_out)(struct file *file, void *fh,
> > +                                   struct v4l2_format *f);
> >
> >       /* VIDIOC_TRY_FMT handlers */
> >       int (*vidioc_try_fmt_vid_cap)(struct file *file, void *fh,
> > @@ -405,6 +435,10 @@ struct v4l2_ioctl_ops {
> >                                      struct v4l2_format *f);
> >       int (*vidioc_try_fmt_meta_out)(struct file *file, void *fh,
> >                                      struct v4l2_format *f);
> > +     int (*vidioc_try_fmt_audio_cap)(struct file *file, void *fh,
> > +                                     struct v4l2_format *f);
> > +     int (*vidioc_try_fmt_audio_out)(struct file *file, void *fh,
> > +                                     struct v4l2_format *f);
> >
> >       /* Buffer handlers */
> >       int (*vidioc_reqbufs)(struct file *file, void *fh,
> > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videod=
ev2.h
> > index 6cd65969c2b5..57c82eb158f1 100644
> > --- a/include/uapi/linux/videodev2.h
> > +++ b/include/uapi/linux/videodev2.h
> > @@ -153,6 +153,8 @@ enum v4l2_buf_type {
> >       V4L2_BUF_TYPE_SDR_OUTPUT           =3D 12,
> >       V4L2_BUF_TYPE_META_CAPTURE         =3D 13,
> >       V4L2_BUF_TYPE_META_OUTPUT          =3D 14,
> > +     V4L2_BUF_TYPE_AUDIO_CAPTURE        =3D 15,
> > +     V4L2_BUF_TYPE_AUDIO_OUTPUT         =3D 16,
> >       /* Deprecated, do not use */
> >       V4L2_BUF_TYPE_PRIVATE              =3D 0x80,
> >  };
> > @@ -169,6 +171,7 @@ enum v4l2_buf_type {
> >        || (type) =3D=3D V4L2_BUF_TYPE_VBI_OUTPUT                  \
> >        || (type) =3D=3D V4L2_BUF_TYPE_SLICED_VBI_OUTPUT           \
> >        || (type) =3D=3D V4L2_BUF_TYPE_SDR_OUTPUT                  \
> > +      || (type) =3D=3D V4L2_BUF_TYPE_AUDIO_OUTPUT                \
> >        || (type) =3D=3D V4L2_BUF_TYPE_META_OUTPUT)
> >
> >  #define V4L2_TYPE_IS_CAPTURE(type) (!V4L2_TYPE_IS_OUTPUT(type))
> > @@ -2423,6 +2426,18 @@ struct v4l2_meta_format {
> >       __u32                           buffersize;
> >  } __attribute__ ((packed));
> >
> > +/**
> > + * struct v4l2_audio_format - audio data format definition
> > + * @audioformat:     little endian four character code (fourcc)
>
> Don't use fourcc here. Instead, use the types defined at snd_pcm_format_t=
.

In the earlier version of this patch series,  fourcc is not used in this
struct v4l2_audio_format.

I use "__u32 audioformat", the value is from snd_pcm_format_t.
Using "__u32" is in order to avoid including the include/uapi/sound/asound.=
h
header.

And defined V4L2_AUDIO_FMT_LPCM for the v4l2_fmtdesc.pixelformat

#define V4L2_AUDIO_FMT_LPCM      v4l2_fourcc('L', 'P', 'C', 'M') /*
audio lpcm */

After discussing with Hans,  I use the current way for v4l audio.

Hans:
Not sure if you can accept going back to the previous solution?
You have already done similar changes in v4l-utils.

Best regards
Shengjiu Wang
>
> > + * @channels:                channel numbers
> > + * @buffersize:              maximum size in bytes required for data
> > + */
> > +struct v4l2_audio_format {
> > +     __u32                           audioformat;
> > +     __u32                           channels;
> > +     __u32                           buffersize;
> > +} __attribute__ ((packed));
> > +
> >  /**
> >   * struct v4l2_format - stream data format
> >   * @type:    enum v4l2_buf_type; type of the data stream
> > @@ -2431,6 +2446,7 @@ struct v4l2_meta_format {
> >   * @win:     definition of an overlaid image
> >   * @vbi:     raw VBI capture or output parameters
> >   * @sliced:  sliced VBI capture or output parameters
> > + * @audio:   definition of an audio format
> >   * @raw_data:        placeholder for future extensions and custom form=
ats
> >   * @fmt:     union of @pix, @pix_mp, @win, @vbi, @sliced, @sdr, @meta
> >   *           and @raw_data
> > @@ -2445,6 +2461,7 @@ struct v4l2_format {
> >               struct v4l2_sliced_vbi_format   sliced;  /* V4L2_BUF_TYPE=
_SLICED_VBI_CAPTURE */
> >               struct v4l2_sdr_format          sdr;     /* V4L2_BUF_TYPE=
_SDR_CAPTURE */
> >               struct v4l2_meta_format         meta;    /* V4L2_BUF_TYPE=
_META_CAPTURE */
> > +             struct v4l2_audio_format        audio;   /* V4L2_BUF_TYPE=
_AUDIO_CAPTURE */
> >               __u8    raw_data[200];                   /* user-defined =
*/
> >       } fmt;
> >  };
>
>
>
> Thanks,
> Mauro