On Wed, Jun 05, 2024 at 06:54:21PM +0200, Jacopo Mondi wrote:
> Add a new format definition for the RkISP1 extensible parameters
> format and document it.
>
> Document the usage of the new format in the rkisp1 admin guide.
>
> Signed-off-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx>
> ---
> Documentation/admin-guide/media/rkisp1.rst | 11 +++-
> .../media/v4l/metafmt-rkisp1.rst | 62 ++++++++++++++++---
> drivers/media/v4l2-core/v4l2-ioctl.c | 1 +
> include/uapi/linux/videodev2.h | 1 +
> 4 files changed, 64 insertions(+), 11 deletions(-)
>
> diff --git a/Documentation/admin-guide/media/rkisp1.rst b/Documentation/admin-guide/media/rkisp1.rst
> index 6f14d9561fa5..934c25e191df 100644
> --- a/Documentation/admin-guide/media/rkisp1.rst
> +++ b/Documentation/admin-guide/media/rkisp1.rst
> @@ -114,11 +114,18 @@ to be applied to the hardware during a video stream, allowing userspace
> to dynamically modify values such as black level, cross talk corrections
> and others.
>
> -The buffer format is defined by struct :c:type:`rkisp1_params_cfg`, and
> -userspace should set
> +The ISP driver supports two different parameters configuration methods, the
> +`fixed parameters format` or the `extensible parameters format`.
> +
> +When using the `fixed parameters` method the buffer format is defined by struct
> +:c:type:`rkisp1_params_cfg`, and userspace set
> :ref:`V4L2_META_FMT_RK_ISP1_PARAMS <v4l2-meta-fmt-rk-isp1-params>` as the
> dataformat.
>
> +When using the fixed parameters method the buffer format is defined by struct
s/fixed/extensible/ ?
> +:c:type:`rkisp1_ext_params_cfg`, and userspace set
> +:ref:`V4L2_META_FMT_RK_ISP1_EXT_PARAMS <v4l2-meta-fmt-rk-isp1-ext-params>` as
> +the dataformat.
>
> Capturing Video Frames Example
> ==============================
> diff --git a/Documentation/userspace-api/media/v4l/metafmt-rkisp1.rst b/Documentation/userspace-api/media/v4l/metafmt-rkisp1.rst
> index fa04f00bcd2e..6ff776d071a3 100644
> --- a/Documentation/userspace-api/media/v4l/metafmt-rkisp1.rst
> +++ b/Documentation/userspace-api/media/v4l/metafmt-rkisp1.rst
> @@ -1,28 +1,72 @@
> .. SPDX-License-Identifier: GPL-2.0
>
> -.. _v4l2-meta-fmt-rk-isp1-params:
> -
> .. _v4l2-meta-fmt-rk-isp1-stat-3a:
>
> -*****************************************************************************
> -V4L2_META_FMT_RK_ISP1_PARAMS ('rk1p'), V4L2_META_FMT_RK_ISP1_STAT_3A ('rk1s')
> -*****************************************************************************
> +************************************************************************************************************************
> +V4L2_META_FMT_RK_ISP1_PARAMS ('rk1p'), V4L2_META_FMT_RK_ISP1_STAT_3A ('rk1s'), V4L2_META_FMT_RK_ISP1_EXT_PARAMS ('rk1e')
> +************************************************************************************************************************
>
> +========================
> Configuration parameters
> ========================
>
> -The configuration parameters are passed to the
> +The configuration of the RkISP1 ISP is performed by userspace by providing
> +parameters for the ISP to the driver using the :c:type:`v4l2_meta_format`
> +interface.
> +
> +There are currently two methods that allow to configure the ISP, the `fixed
> +parameters` configuration format and the `extensible parameters` configuration
> +format.
> +
> +.. _v4l2-meta-fmt-rk-isp1-params:
> +
> +Fixed parameters configuration format
> +=====================================
> +
> +When using the fixed configuration format, parameters are passed to the
> :ref:`rkisp1_params <rkisp1_params>` metadata output video node, using
> -the :c:type:`v4l2_meta_format` interface. The buffer contains
> -a single instance of the C structure :c:type:`rkisp1_params_cfg` defined in
> -``rkisp1-config.h``. So the structure can be obtained from the buffer by:
> +the `V4L2_META_FMT_RK_ISP1_PARAMS` meta pixel format.
> +
> +The buffer contains a single instance of the C structure
> +:c:type:`rkisp1_params_cfg` defined in ``rkisp1-config.h``. So the structure can
> +be obtained from the buffer by:
>
> .. code-block:: c
>
> struct rkisp1_params_cfg *params = (struct rkisp1_params_cfg*) buffer;
>
> +As the members of :c:type:`rkisp1_params_cfg` are defined in the
> +``rkisp1-config.h`` header, the structure layout is immutable and cannot be
> +extended further. For this reason the fixed configuration format only allows the
> +configuration of the ISP blocks supported at the time when the structure had
> +been defined in the header file, as introducing new parameters or modifying the
> +existing ones would change the buffer layout and cause breakages in existing
> +applications.
> +
> +.. _v4l2-meta-fmt-rk-isp1-ext-params:
> +
> +Extensible parameters configuration format
> +==========================================
> +
> +When using the extensible configuration format, parameters are passed to the
> +:ref:`rkisp1_params <rkisp1_params>` metadata output video node, using
> +the `V4L2_META_FMT_RK_ISP1_EXT_PARAMS` meta pixel format.
> +
> +The buffer contains a single instance of the C structure
> +:c:type:`rkisp1_ext_params_cfg` defined in ``rkisp1-config.h``. The
> +:c:type:`rkisp1_ext_params_cfg` structure is designed to allow userspace to
> +populate the data buffer with only the configuration data for the ISP block it
> +intends to configure. The extensible parameters format design allows to define
s/allows to define/allows defining/
> +new block types and new configuration parameters and defines a versioning scheme
s/parameters/parameters,/
Reviewed-by: Paul Elder <paul.elder@xxxxxxxxxxxxxxxx>
> +so that it can be extended and versioned without breaking compatibility with
> +existing applications.
> +
> +For these reasons, this configuration method if preferred over the `fixed
> +parameters` format alternative.
> +
> .. rkisp1_stat_buffer
>
> +===========================
> 3A and histogram statistics
> ===========================
>
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index 4c76d17b4629..aefdc1efd24b 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_META_FMT_VIVID: descr = "Vivid Metadata"; break;
> case V4L2_META_FMT_RK_ISP1_PARAMS: descr = "Rockchip ISP1 3A Parameters"; break;
> case V4L2_META_FMT_RK_ISP1_STAT_3A: descr = "Rockchip ISP1 3A Statistics"; break;
> + case V4L2_META_FMT_RK_ISP1_EXT_PARAMS: descr = "Rockchip ISP1 Ext 3A Params"; break;
> case V4L2_PIX_FMT_NV12_8L128: descr = "NV12 (8x128 Linear)"; break;
> case V4L2_PIX_FMT_NV12M_8L128: descr = "NV12M (8x128 Linear)"; break;
> case V4L2_PIX_FMT_NV12_10BE_8L128: descr = "10-bit NV12 (8x128 Linear, BE)"; break;
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index fe6b67e83751..7c2a303c6f59 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -840,6 +840,7 @@ struct v4l2_pix_format {
> /* Vendor specific - used for RK_ISP1 camera sub-system */
> #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 */
> +#define V4L2_META_FMT_RK_ISP1_EXT_PARAMS v4l2_fourcc('R', 'K', '1', 'E') /* Rockchip ISP1 3a Extensible Parameters */
>
> #ifdef __KERNEL__
> /*
> --
> 2.45.1
>
