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Date:   Fri, 28 Jul 2023 07:59:33 +0000
From:   Tomasz Figa <tfiga@chromium.org>
To:     Shengjiu Wang <shengjiu.wang@nxp.com>
Cc:     hverkuil@xs4all.nl, sakari.ailus@iki.fi, m.szyprowski@samsung.com,
        mchehab@kernel.org, linux-media@vger.kernel.org,
        linux-kernel@vger.kernel.org, shengjiu.wang@gmail.com,
        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
Subject: Re: [RFC PATCH v2 4/7] media: v4l2: Add audio capture and output
 support
Message-ID: <20230728075933.pdepqspznenazs5f@chromium.org>
References: <1690265540-25999-1-git-send-email-shengjiu.wang@nxp.com>
 <1690265540-25999-5-git-send-email-shengjiu.wang@nxp.com>
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In-Reply-To: <1690265540-25999-5-git-send-email-shengjiu.wang@nxp.com>
Precedence: bulk

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
>