[v3,5/9] media: uapi: Add meta pixel format for PiSP BE config

  Add format description for the PiSP Back End configuration parameter
buffer.

Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
 .../userspace-api/media/v4l/meta-formats.rst  |  1 +
 .../media/v4l/metafmt-pisp-be.rst             | 46 +++++++++++++++++++
 drivers/media/v4l2-core/v4l2-ioctl.c          |  1 +
 include/uapi/linux/videodev2.h                |  3 ++
 4 files changed, 51 insertions(+)
 create mode 100644 Documentation/userspace-api/media/v4l/metafmt-pisp-be.rst
  

Hi Jacopo,

Thank you for this work.

On Tue, 5 Mar 2024 at 16:09, Jacopo Mondi <jacopo.mondi@ideasonboard.com> wrote:
>
> Add format description for the PiSP Back End configuration parameter
> buffer.
>
> Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>

Reviewed-by: Naushir Patuck <naush@raspberrypi.com>

> ---
>  .../userspace-api/media/v4l/meta-formats.rst  |  1 +
>  .../media/v4l/metafmt-pisp-be.rst             | 46 +++++++++++++++++++
>  drivers/media/v4l2-core/v4l2-ioctl.c          |  1 +
>  include/uapi/linux/videodev2.h                |  3 ++
>  4 files changed, 51 insertions(+)
>  create mode 100644 Documentation/userspace-api/media/v4l/metafmt-pisp-be.rst
>
> diff --git a/Documentation/userspace-api/media/v4l/meta-formats.rst b/Documentation/userspace-api/media/v4l/meta-formats.rst
> index 0bb61fc5bc00..d96ff1ea3373 100644
> --- a/Documentation/userspace-api/media/v4l/meta-formats.rst
> +++ b/Documentation/userspace-api/media/v4l/meta-formats.rst
> @@ -14,6 +14,7 @@ These formats are used for the :ref:`metadata` interface only.
>
>      metafmt-d4xx
>      metafmt-intel-ipu3
> +    metafmt-pisp-be
>      metafmt-rkisp1
>      metafmt-uvc
>      metafmt-vsp1-hgo
> diff --git a/Documentation/userspace-api/media/v4l/metafmt-pisp-be.rst b/Documentation/userspace-api/media/v4l/metafmt-pisp-be.rst
> new file mode 100644
> index 000000000000..f3d30ba989b3
> --- /dev/null
> +++ b/Documentation/userspace-api/media/v4l/metafmt-pisp-be.rst
> @@ -0,0 +1,46 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +.. _v4l2-meta-fmt-rpi-be-cfg:
> +
> +************************
> +V4L2_META_FMT_RPI_BE_CFG
> +************************
> +
> +Raspberry Pi PiSP Back End configuration format
> +===============================================
> +
> +The Raspberry Pi PiSP Back End memory-to-memory image signal processor is
> +configured by userspace by providing a buffer of configuration parameters
> +to the `pispbe-config` output video device node using the
> +:c:type:`v4l2_meta_format` interface.
> +
> +The PiSP Back End processes images in tiles, and its configuration requires
> +specifying two different sets of parameters by populating the members of
> +:c:type:`pisp_be_tiles_config` defined in the ``pisp_be_config.h`` header file.
> +
> +The `Raspberry Pi PiSP technical specification
> +<https://datasheets.raspberrypi.com/camera/raspberry-pi-image-signal-processor-specification.pdf>_`
> +provide detailed description of the ISP back end configuration and programming
> +model.
> +
> +Global configuration data
> +-------------------------
> +
> +The global configuration data describe how the pixels in a particular image are
> +to be processed and is therefore shared across all the tiles of the image. So
> +for example, LSC (Lens Shading Correction) or Denoise parameters would be common
> +across all tiles from the same frame.
> +
> +Global configuration data are passed to the ISP by populating the member of
> +:c:type:`pisp_be_config`.
> +
> +Tile parameters
> +---------------
> +
> +As the ISP processes images in tiles, each set of tiles parameters describe how
> +a single tile in an image is going to be processed. A single set of tile
> +parameters consist of 160 bytes of data and to process a batch of tiles several
> +sets of tiles parameters are required.
> +
> +Tiles parameters are passed to the ISP by populating the member of
> +:c:type:`pisp_tile` and the :c:type:`num_tiles` field.
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index a2f9c446a565..18e9aa1297e1 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -1456,6 +1456,7 @@ 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_META_FMT_RPI_BE_CFG:  descr = "RPi PiSP BE Config format"; break;
>
>         default:
>                 /* Compressed formats */
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 89b2b409fc03..c3daf61f43d5 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -845,6 +845,9 @@ 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 */
>
> +/* Vendor specific - used for RaspberryPi PiSP */
> +#define V4L2_META_FMT_RPI_BE_CFG v4l2_fourcc('R', 'P', 'B', 'C') /* PiSP BE configuration */
> +
>  /* priv field value to indicates that subsequent fields are valid. */
>  #define V4L2_PIX_FMT_PRIV_MAGIC                0xfeedcafe
>
> --
> 2.43.2
>