Re: [PATCH v13 09/16] media: uapi: Define audio sample format fourcc type

[Nicolas Dufresne]

Le lundi 26 février 2024 à 16:28 +0800, Shengjiu Wang a écrit :
> The audio sample format definition is from alsa,
> the header file is include/uapi/sound/asound.h, but
> don't include this header file directly, because in
> user space, there is another copy in alsa-lib.
> There will be conflict in userspace for include
> videodev2.h & asound.h and asoundlib.h
> 
> Here still use the fourcc format.

I'd like to join Mauro's voice that duplicating the audio formats is a bad idea.
We have the same issues with video formats when you look at V4L2 vs DRM. You're
rationale is that videodev2.h will be ambiguous if it includes asound.h, but
looking at this change, there is no reason why you need to include asound.h in
videodev2.h at all. The format type can be abstracted out with a uint32 in the
API, and then it would be up to the users to include and use the appropriate
formats IDs.

Nicolas

> 
> Signed-off-by: Shengjiu Wang <shengjiu.wang@xxxxxxx>
> ---
>  .../userspace-api/media/v4l/pixfmt-audio.rst  | 87 +++++++++++++++++++
>  .../userspace-api/media/v4l/pixfmt.rst        |  1 +
>  drivers/media/v4l2-core/v4l2-ioctl.c          | 13 +++
>  include/uapi/linux/videodev2.h                | 23 +++++
>  4 files changed, 124 insertions(+)
>  create mode 100644 Documentation/userspace-api/media/v4l/pixfmt-audio.rst
> 
> diff --git a/Documentation/userspace-api/media/v4l/pixfmt-audio.rst b/Documentation/userspace-api/media/v4l/pixfmt-audio.rst
> new file mode 100644
> index 000000000000..04b4a7fbd8f4
> --- /dev/null
> +++ b/Documentation/userspace-api/media/v4l/pixfmt-audio.rst
> @@ -0,0 +1,87 @@
> +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
> +
> +.. _pixfmt-audio:
> +
> +*************
> +Audio Formats
> +*************
> +
> +These formats are used for :ref:`audiomem2mem` interface only.
> +
> +.. tabularcolumns:: |p{5.8cm}|p{1.2cm}|p{10.3cm}|
> +
> +.. cssclass:: longtable
> +
> +.. flat-table:: Audio Format
> +    :header-rows:  1
> +    :stub-columns: 0
> +    :widths:       3 1 4
> +
> +    * - Identifier
> +      - Code
> +      - Details
> +    * .. _V4L2-AUDIO-FMT-S8:
> +
> +      - ``V4L2_AUDIO_FMT_S8``
> +      - 'S8'
> +      - Corresponds to SNDRV_PCM_FORMAT_S8 in ALSA
> +    * .. _V4L2-AUDIO-FMT-S16-LE:
> +
> +      - ``V4L2_AUDIO_FMT_S16_LE``
> +      - 'S16_LE'
> +      - Corresponds to SNDRV_PCM_FORMAT_S16_LE in ALSA
> +    * .. _V4L2-AUDIO-FMT-U16-LE:
> +
> +      - ``V4L2_AUDIO_FMT_U16_LE``
> +      - 'U16_LE'
> +      - Corresponds to SNDRV_PCM_FORMAT_U16_LE in ALSA
> +    * .. _V4L2-AUDIO-FMT-S24-LE:
> +
> +      - ``V4L2_AUDIO_FMT_S24_LE``
> +      - 'S24_LE'
> +      - Corresponds to SNDRV_PCM_FORMAT_S24_LE in ALSA
> +    * .. _V4L2-AUDIO-FMT-U24-LE:
> +
> +      - ``V4L2_AUDIO_FMT_U24_LE``
> +      - 'U24_LE'
> +      - Corresponds to SNDRV_PCM_FORMAT_U24_LE in ALSA
> +    * .. _V4L2-AUDIO-FMT-S32-LE:
> +
> +      - ``V4L2_AUDIO_FMT_S32_LE``
> +      - 'S32_LE'
> +      - Corresponds to SNDRV_PCM_FORMAT_S32_LE in ALSA
> +    * .. _V4L2-AUDIO-FMT-U32-LE:
> +
> +      - ``V4L2_AUDIO_FMT_U32_LE``
> +      - 'U32_LE'
> +      - Corresponds to SNDRV_PCM_FORMAT_U32_LE in ALSA
> +    * .. _V4L2-AUDIO-FMT-FLOAT-LE:
> +
> +      - ``V4L2_AUDIO_FMT_FLOAT_LE``
> +      - 'FLOAT_LE'
> +      - Corresponds to SNDRV_PCM_FORMAT_FLOAT_LE in ALSA
> +    * .. _V4L2-AUDIO-FMT-IEC958-SUBFRAME-LE:
> +
> +      - ``V4L2_AUDIO_FMT_IEC958_SUBFRAME_LE``
> +      - 'IEC958_SUBFRAME_LE'
> +      - Corresponds to SNDRV_PCM_FORMAT_IEC958_SUBFRAME_LE in ALSA
> +    * .. _V4L2-AUDIO-FMT-S24-3LE:
> +
> +      - ``V4L2_AUDIO_FMT_S24_3LE``
> +      - 'S24_3LE'
> +      - Corresponds to SNDRV_PCM_FORMAT_S24_3LE in ALSA
> +    * .. _V4L2-AUDIO-FMT-U24-3LE:
> +
> +      - ``V4L2_AUDIO_FMT_U24_3LE``
> +      - 'U24_3LE'
> +      - Corresponds to SNDRV_PCM_FORMAT_U24_3LE in ALSA
> +    * .. _V4L2-AUDIO-FMT-S20-3LE:
> +
> +      - ``V4L2_AUDIO_FMT_S20_3LE``
> +      - 'S20_3LE'
> +      - Corresponds to SNDRV_PCM_FORMAT_S24_3LE in ALSA
> +    * .. _V4L2-AUDIO-FMT-U20-3LE:
> +
> +      - ``V4L2_AUDIO_FMT_U20_3LE``
> +      - 'U20_3LE'
> +      - Corresponds to SNDRV_PCM_FORMAT_U20_3LE in ALSA
> diff --git a/Documentation/userspace-api/media/v4l/pixfmt.rst b/Documentation/userspace-api/media/v4l/pixfmt.rst
> index 11dab4a90630..2eb6fdd3b43d 100644
> --- a/Documentation/userspace-api/media/v4l/pixfmt.rst
> +++ b/Documentation/userspace-api/media/v4l/pixfmt.rst
> @@ -36,3 +36,4 @@ see also :ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>`.)
>      colorspaces
>      colorspaces-defs
>      colorspaces-details
> +    pixfmt-audio
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index 961abcdf7290..be229c69e991 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -1471,6 +1471,19 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
>  	case V4L2_PIX_FMT_Y210:		descr = "10-bit YUYV Packed"; break;
>  	case V4L2_PIX_FMT_Y212:		descr = "12-bit YUYV Packed"; break;
>  	case V4L2_PIX_FMT_Y216:		descr = "16-bit YUYV Packed"; break;
> +	case V4L2_AUDIO_FMT_S8:		descr = "8-bit Signed"; break;
> +	case V4L2_AUDIO_FMT_S16_LE:	descr = "16-bit Signed LE"; break;
> +	case V4L2_AUDIO_FMT_U16_LE:		descr = "16-bit Unsigned LE"; break;
> +	case V4L2_AUDIO_FMT_S24_LE:		descr = "24(32)-bit Signed LE"; break;
> +	case V4L2_AUDIO_FMT_U24_LE:		descr = "24(32)-bit Unsigned LE"; break;
> +	case V4L2_AUDIO_FMT_S32_LE:		descr = "32-bit Signed LE"; break;
> +	case V4L2_AUDIO_FMT_U32_LE:		descr = "32-bit Unsigned LE"; break;
> +	case V4L2_AUDIO_FMT_FLOAT_LE:		descr = "32-bit Float LE"; break;
> +	case V4L2_AUDIO_FMT_IEC958_SUBFRAME_LE:	descr = "32-bit IEC958 LE"; break;
> +	case V4L2_AUDIO_FMT_S24_3LE:		descr = "24(24)-bit Signed LE"; break;
> +	case V4L2_AUDIO_FMT_U24_3LE:		descr = "24(24)-bit Unsigned LE"; break;
> +	case V4L2_AUDIO_FMT_S20_3LE:		descr = "20(24)-bit Signed LE"; break;
> +	case V4L2_AUDIO_FMT_U20_3LE:		descr = "20(24)-bit Unsigned LE"; break;
>  
>  	default:
>  		/* Compressed formats */
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 2c03d2dfadbe..673a6235a029 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -843,6 +843,29 @@ struct v4l2_pix_format {
>  #define V4L2_META_FMT_RK_ISP1_PARAMS	v4l2_fourcc('R', 'K', '1', 'P') /* Rockchip ISP1 3A Parameters */
>  #define V4L2_META_FMT_RK_ISP1_STAT_3A	v4l2_fourcc('R', 'K', '1', 'S') /* Rockchip ISP1 3A Statistics */
>  
> +/*
> + * Audio-data formats
> + * All these audio formats use a fourcc starting with 'AU'
> + * followed by the SNDRV_PCM_FORMAT_ value from asound.h.
> + */
> +#define V4L2_AUDIO_FMT_S8			v4l2_fourcc('A', 'U', '0', '0')
> +#define V4L2_AUDIO_FMT_S16_LE			v4l2_fourcc('A', 'U', '0', '2')
> +#define V4L2_AUDIO_FMT_U16_LE			v4l2_fourcc('A', 'U', '0', '4')
> +#define V4L2_AUDIO_FMT_S24_LE			v4l2_fourcc('A', 'U', '0', '6')
> +#define V4L2_AUDIO_FMT_U24_LE			v4l2_fourcc('A', 'U', '0', '8')
> +#define V4L2_AUDIO_FMT_S32_LE			v4l2_fourcc('A', 'U', '1', '0')
> +#define V4L2_AUDIO_FMT_U32_LE			v4l2_fourcc('A', 'U', '1', '2')
> +#define V4L2_AUDIO_FMT_FLOAT_LE			v4l2_fourcc('A', 'U', '1', '4')
> +#define V4L2_AUDIO_FMT_IEC958_SUBFRAME_LE	v4l2_fourcc('A', 'U', '1', '8')
> +#define V4L2_AUDIO_FMT_S24_3LE			v4l2_fourcc('A', 'U', '3', '2')
> +#define V4L2_AUDIO_FMT_U24_3LE			v4l2_fourcc('A', 'U', '3', '4')
> +#define V4L2_AUDIO_FMT_S20_3LE			v4l2_fourcc('A', 'U', '3', '6')
> +#define V4L2_AUDIO_FMT_U20_3LE			v4l2_fourcc('A', 'U', '3', '8')
> +
> +#define v4l2_fourcc_to_audfmt(fourcc)	\
> +	(__force snd_pcm_format_t)(((((fourcc) >> 16) & 0xff) - '0') * 10  \
> +				   + ((((fourcc) >> 24) & 0xff) - '0'))
> +
>  /* priv field value to indicates that subsequent fields are valid. */
>  #define V4L2_PIX_FMT_PRIV_MAGIC		0xfeedcafe
>