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

On Tue, Aug 1, 2023 at 6:47 PM Shengjiu Wang shengjiu.wang@gmail.com wrote:

On Fri, Jul 28, 2023 at 3:59 PM Tomasz Figa tfiga@chromium.org wrote:

...

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.

Thanks for reviewing.

Sorry for sending again for using the plain text mode.

...

...

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?

Ok, will change to use "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 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.

The range for sample rate is [5512, 768000]. The format is defined in include/uapi/sound/asound.h, they are SNDRV_PCM_FORMAT_S8, SNDRV_PCM_FORMAT_U8, ...

Where should I put these info?

I see, so those are standard definitions of the sound subsystem. I think we should refer to the right header and/or data types in the kerneldoc comment for the struct. We also need to provide the sphinx documentation for the new device type and extend the description of relevant ioctls (e.g. VIDIOC_S_FMT) that accept the new structs. I.e. the v4l2_format struct used by VIDIOC_S_FMT is documented in

https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/vidioc-g-fmt....

and there is documentation for each of the union members, like v4l2_pix_format_mplane that is commonly used for video data:

https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/pixfmt-v4l2-m...

We'll need a similar one for the new v4l2_audio_format.

Best regards, Tomasz

Best regards Wang shengjiu

...

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