Re: [PATCH v10 6/9] media: uapi: Add a control for HANTRO driver

[Ezequiel Garcia]

On Tue, 2021-04-20 at 14:10 +0200, Benjamin Gaignard wrote:
> The HEVC HANTRO driver needs to know the number of bits to skip at
> the beginning of the slice header.
> That is a hardware specific requirement so create a dedicated control
> for this purpose.
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>

Reviewed-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>

> ---
>  .../userspace-api/media/drivers/hantro.rst    | 19 +++++++++++++++++++
>  .../userspace-api/media/drivers/index.rst     |  1 +
>  include/media/hevc-ctrls.h                    | 13 +++++++++++++
>  3 files changed, 33 insertions(+)
>  create mode 100644 Documentation/userspace-api/media/drivers/hantro.rst
> 
> diff --git a/Documentation/userspace-api/media/drivers/hantro.rst b/Documentation/userspace-api/media/drivers/hantro.rst
> new file mode 100644
> index 000000000000..cd9754b4e005
> --- /dev/null
> +++ b/Documentation/userspace-api/media/drivers/hantro.rst
> @@ -0,0 +1,19 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +Hantro video decoder driver
> +===========================
> +
> +The Hantro video decoder driver implements the following driver-specific controls:
> +
> +``V4L2_CID_HANTRO_HEVC_SLICE_HEADER_SKIP (integer)``
> +    Specifies to Hantro HEVC video decoder driver the number of data (in bits) to
> +    skip in the slice segment header.
> +    If non-IDR, the bits to be skipped go from syntax element "pic_output_flag"
> +    to before syntax element "slice_temporal_mvp_enabled_flag".
> +    If IDR, the skipped bits are just "pic_output_flag"
> +    (separate_colour_plane_flag is not supported).
> +
> +.. note::
> +
> +        This control is not yet part of the public kernel API and
> +        it is expected to change.
> diff --git a/Documentation/userspace-api/media/drivers/index.rst b/Documentation/userspace-api/media/drivers/index.rst
> index 1a9038f5f9fa..12e3c512d718 100644
> --- a/Documentation/userspace-api/media/drivers/index.rst
> +++ b/Documentation/userspace-api/media/drivers/index.rst
> @@ -33,6 +33,7 @@ For more details see the file COPYING in the source distribution of Linux.
>  
>         ccs
>         cx2341x-uapi
> +        hantro
>         imx-uapi
>         max2175
>         meye-uapi
> diff --git a/include/media/hevc-ctrls.h b/include/media/hevc-ctrls.h
> index 8e0109eea454..b713eeed1915 100644
> --- a/include/media/hevc-ctrls.h
> +++ b/include/media/hevc-ctrls.h
> @@ -224,4 +224,17 @@ struct v4l2_ctrl_hevc_decode_params {
>         __u64   flags;
>  };
>  
> +/*  MPEG-class control IDs specific to the Hantro driver as defined by V4L2 */
> +#define V4L2_CID_CODEC_HANTRO_BASE                             (V4L2_CTRL_CLASS_CODEC | 0x1200)
> +/*
> + * V4L2_CID_HANTRO_HEVC_SLICE_HEADER_SKIP -
> + * the number of data (in bits) to skip in the
> + * slice segment header.
> + * If non-IDR, the bits to be skipped go from syntax element "pic_output_flag"
> + * to before syntax element "slice_temporal_mvp_enabled_flag".
> + * If IDR, the skipped bits are just "pic_output_flag"
> + * (separate_colour_plane_flag is not supported).
> + */
> +#define V4L2_CID_HANTRO_HEVC_SLICE_HEADER_SKIP (V4L2_CID_CODEC_HANTRO_BASE + 0)
> +
>  #endif