Re: [RFC PATCH v2 4/7] media: v4l2: Add audio capture and output support

Tomasz Figa
2023-07-28T08:01:25Z

Hi Shengjiu,

On Tue, Jul 25, 2023 at 02:12:17PM +0800, Shengjiu Wang wrote:
> 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/audioX".
>
> Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
> ---
> .../media/common/videobuf2/videobuf2-v4l2.c | 4 ++
> drivers/media/v4l2-core/v4l2-dev.c | 17 ++++++
> drivers/media/v4l2-core/v4l2-ioctl.c | 52 +++++++++++++++++++
> include/media/v4l2-dev.h | 2 +
> include/media/v4l2-ioctl.h | 34 ++++++++++++
> include/uapi/linux/videodev2.h | 19 +++++++
> 6 files changed, 128 insertions(+)
>

Thanks for the patch! Please check my comments inline.

> diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> index c7a54d82a55e..12f2be2773a2 100644
> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> @@ -785,6 +785,10 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
> case V4L2_BUF_TYPE_META_OUTPUT:
> requested_sizes[0] = f->fmt.meta.buffersize;
> break;
> + case V4L2_BUF_TYPE_AUDIO_CAPTURE:
> + case V4L2_BUF_TYPE_AUDIO_OUTPUT:
> + requested_sizes[0] = f->fmt.audio.buffersize;
> + break;
> default:
> return -EINVAL;
> }
> diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
> index f81279492682..67484f4c6eaf 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_device *vdev)
> bool is_tch = vdev->vfl_type == VFL_TYPE_TOUCH;
> bool is_meta = vdev->vfl_type == VFL_TYPE_VIDEO &&
> (vdev->device_caps & meta_caps);
> + bool is_audio = vdev->vfl_type == VFL_TYPE_AUDIO;
> bool is_rx = vdev->vfl_dir != VFL_DIR_TX;
> bool is_tx = vdev->vfl_dir != VFL_DIR_RX;
> bool is_io_mc = vdev->device_caps & V4L2_CAP_IO_MC;
> @@ -664,6 +665,19 @@ static void determine_valid_ioctls(struct video_device *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_audio_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_audio_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 ||
> @@ -927,6 +941,9 @@ int __video_register_device(struct video_device *vdev,
> case VFL_TYPE_TOUCH:
> name_base = "v4l-touch";
> break;
> + case VFL_TYPE_AUDIO:
> + name_base = "audio";

I think it was mentioned before that "audio" could be confusing. Wasn't
there actually some other kind of /dev/audio device long ago?

Seems like for touch, "v4l-touch" was introduced. Maybe it would also
make sense to call it "v4l-audio" for 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 01ba27f2ef87..aa9d872bba8d 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[] = {
> [V4L2_BUF_TYPE_SDR_OUTPUT] = "sdr-out",
> [V4L2_BUF_TYPE_META_CAPTURE] = "meta-cap",
> [V4L2_BUF_TYPE_META_OUTPUT] = "meta-out",
> + [V4L2_BUF_TYPE_AUDIO_CAPTURE] = "audio-cap",
> + [V4L2_BUF_TYPE_AUDIO_OUTPUT] = "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 +349,12 @@ static void v4l_print_format(const void *arg, bool write_only)
> pr_cont(", dataformat=%p4cc, buffersize=%u\n",
> &pixelformat, meta->buffersize);
> break;
> + case V4L2_BUF_TYPE_AUDIO_CAPTURE:
> + case V4L2_BUF_TYPE_AUDIO_OUTPUT:
> + audio = &p->fmt.audio;
> + pr_cont(", rate=%u, format=%u, channels=%u, buffersize=%u\n",
> + audio->rate, audio->format, audio->channels, audio->buffersize);
> + break;
> }
> }
>
> @@ -927,6 +936,7 @@ static int check_fmt(struct file *file, enum v4l2_buf_type type)
> bool is_tch = vfd->vfl_type == VFL_TYPE_TOUCH;
> bool is_meta = vfd->vfl_type == VFL_TYPE_VIDEO &&
> (vfd->device_caps & meta_caps);
> + bool is_audio = vfd->vfl_type == VFL_TYPE_AUDIO;
> bool is_rx = vfd->vfl_dir != VFL_DIR_TX;
> bool is_tx = vfd->vfl_dir != VFL_DIR_RX;
>
> @@ -992,6 +1002,14 @@ 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;
> }
> @@ -1594,6 +1612,16 @@ static int v4l_enum_fmt(const struct v4l2_ioctl_ops *ops,
> break;
> ret = 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 = 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 = ops->vidioc_enum_fmt_audio_out(file, fh, arg);
> + break;
> }
> if (ret == 0)
> v4l_fill_fmtdesc(p);
> @@ -1670,6 +1698,10 @@ 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;
> }
> @@ -1781,6 +1813,16 @@ 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;
> }
> @@ -1889,6 +1931,16 @@ static int v4l_try_fmt(const struct v4l2_ioctl_ops *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 e0a13505f88d..0924e6d1dab1 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 input/output devices
> * @VFL_TYPE_MAX: number of VFL types, must always be last in the enum
> */
> 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 capture
> * @vidioc_g_fmt_meta_out: pointer to the function that implements
> * :ref:`VIDIOC_G_FMT <vidioc_g_fmt>` ioctl logic for metadata output
> + * @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 capture
> * @vidioc_s_fmt_meta_out: pointer to the function that implements
> * :ref:`VIDIOC_S_FMT <vidioc_g_fmt>` ioctl logic for metadata output
> + * @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 capture
> * in single plane mode
> @@ -149,6 +163,10 @@ struct v4l2_fh;
> * :ref:`VIDIOC_TRY_FMT <vidioc_g_fmt>` ioctl logic for metadata capture
> * @vidioc_try_fmt_meta_out: pointer to the function that implements
> * :ref:`VIDIOC_TRY_FMT <vidioc_g_fmt>` ioctl logic for metadata output
> + * @vidioc_try_fmt_audio_cap: pointer to the function that implements
> + * :ref:`VIDIOC_TRY_FMT <vidioc_g_fmt>` ioctl logic for audio capture
> + * @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/videodev2.h
> index 3af6a82d0cad..e5051410928a 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 = 12,
> V4L2_BUF_TYPE_META_CAPTURE = 13,
> V4L2_BUF_TYPE_META_OUTPUT = 14,
> + V4L2_BUF_TYPE_AUDIO_CAPTURE = 15,
> + V4L2_BUF_TYPE_AUDIO_OUTPUT = 16,
> /* Deprecated, do not use */
> V4L2_BUF_TYPE_PRIVATE = 0x80,
> };
> @@ -169,6 +171,7 @@ enum v4l2_buf_type {
> || (type) == V4L2_BUF_TYPE_VBI_OUTPUT \
> || (type) == V4L2_BUF_TYPE_SLICED_VBI_OUTPUT \
> || (type) == V4L2_BUF_TYPE_SDR_OUTPUT \
> + || (type) == V4L2_BUF_TYPE_AUDIO_OUTPUT \
> || (type) == V4L2_BUF_TYPE_META_OUTPUT)
>
> #define V4L2_TYPE_IS_CAPTURE(type) (!V4L2_TYPE_IS_OUTPUT(type))
> @@ -2415,6 +2418,20 @@ struct v4l2_meta_format {
> __u32 buffersize;
> } __attribute__ ((packed));
>
> +/**
> + * struct v4l2_audio_format - audio data format definition
> + * @rate: sample rate
> + * @format: sample format
> + * @channels: channel numbers
> + * @buffersize: maximum size in bytes required for data
> + */
> +struct v4l2_audio_format {
> + __u32 rate;
> + __u32 format;

What are the values for the rate and format fields? Since they are part
of the UAPI, they need to be defined.

Best regards,
Tomasz

> + __u32 channels;
> + __u32 buffersize;
> +} __attribute__ ((packed));
> +
> /**
> * struct v4l2_format - stream data format
> * @type: enum v4l2_buf_type; type of the data stream
> @@ -2423,6 +2440,7 @@ 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 formats
> * @fmt: union of @pix, @pix_mp, @win, @vbi, @sliced, @sdr, @meta
> * and @raw_data
> @@ -2437,6 +2455,7 @@ 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;
> };
> --
> 2.34.1
>