Re: [PATCHv2 1/2] v4l: Define a pixel format for the R-Car VSP1 2-D histogram engine

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Niklas,

Thank you for the patch.

On Tuesday 06 Sep 2016 16:38:55 Niklas Söderlund wrote:
> The format is used on the R-Car VSP1 video queues that carry
> 2-D histogram statistics data.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> ---
>  Documentation/media/uapi/v4l/meta-formats.rst      |   1 +
>  .../media/uapi/v4l/pixfmt-meta-vsp1-hgt.rst        | 122 ++++++++++++++++++
>  drivers/media/v4l2-core/v4l2-ioctl.c               |   1 +
>  include/uapi/linux/videodev2.h                     |   3 +-
>  4 files changed, 126 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/media/uapi/v4l/pixfmt-meta-vsp1-hgt.rst
> 
> diff --git a/Documentation/media/uapi/v4l/meta-formats.rst
> b/Documentation/media/uapi/v4l/meta-formats.rst index 05ab91e..01e24e3
> 100644
> --- a/Documentation/media/uapi/v4l/meta-formats.rst
> +++ b/Documentation/media/uapi/v4l/meta-formats.rst
> @@ -13,3 +13,4 @@ These formats are used for the :ref:`metadata` interface
> only.
>      :maxdepth: 1
> 
>      pixfmt-meta-vsp1-hgo
> +    pixfmt-meta-vsp1-hgt
> diff --git a/Documentation/media/uapi/v4l/pixfmt-meta-vsp1-hgt.rst
> b/Documentation/media/uapi/v4l/pixfmt-meta-vsp1-hgt.rst new file mode
> 100644
> index 0000000..0393148
> --- /dev/null
> +++ b/Documentation/media/uapi/v4l/pixfmt-meta-vsp1-hgt.rst
> @@ -0,0 +1,122 @@
> +.. -*- coding: utf-8; mode: rst -*-
> +
> +.. _v4l2-meta-fmt-vsp1-hgt:
> +
> +*******************************
> +V4L2_META_FMT_VSP1_HGT ('VSPT')
> +*******************************
> +
> +*man V4L2_META_FMT_VSP1_HGT(2)*
> +
> +Renesas R-Car VSP1 2-D Histogram Data
> +
> +
> +Description
> +===========
> +
> +This format describes histogram data generated by the Renesas R-Car VSP1
> +2-D Histogram (HGT) engine.
> +
> +The VSP1 HGT is a histogram computation engine that operates on HSV
> +data. It operates on a possibly cropped and subsampled input image and
> +computes the sum, maximum and minimum of the S component as well as a
> +weighted frequency histogram based on the H and S components.
> +
> +The histogram is a matrix of 6 Hue and 32 Saturation buckets, 192 in
> +total. Each HSV value is added to one or more buckets with a weight
> +between 1 and 16 depending on the Hue areas configuration. Finding the
> +corresponding buckets is done by inspecting the H and S value
> independently. +
> +The Saturation position **n** (0 - 31) of the bucket in the matrix is
> +found by the expression:
> +
> +    n = S / 8
> +
> +The Hue position **m** (0 - 5) of the bucket in the matrix depends on
> +how the HGT Hue areas are configured. There are 6 user configurable Hue
> +Areas which can be configured to cover overlapping Hue values:
> +
> +::
> +
> +         Area 0       Area 1       Area 2       Area 3       Area 4      
> Area 5 +        ________     ________     ________     ________    
> ________     ________ +   \   /|      |\   /|      |\   /|      |\   /|    
>  |\   /|      |\   /|      |\   / +    \ / |      | \ / |      | \ / |     
> | \ / |      | \ / |      | \ / |      | \ / +     X  |      |  X  |      |
>  X  |      |  X  |      |  X  |      |  X  |      |  X +    / \ |      | /
> \ |      | / \ |      | / \ |      | / \ |      | / \ |      | / \ +   /  
> \|      |/   \|      |/   \|      |/   \|      |/   \|      |/   \|      |/
>   \ +  5U   0L      0U   1L      1U   2L      2U   3L      3U   4L      4U 
>  5L      5U   0L +        <0..............................Hue
> Value............................255> +
> +When two consecutive areas don't overlap (n+1L is equal to nU) the boundary
> +value is considered as part of the lower area.
> +
> +Pixels with a hue value included in the centre of an area (between nL and
> nU +included) are are attributed to that single area and given a weight of

s/are are/are/

> 16. +Pixels with a hue value included in the overlapping region between two
> areas +(between n+1L and nU excluded) are attributed to both areas and
> given a weight +for each of these areas proportional to their position
> along the diagonal +lines (rounded down)."

s/"//

Apart from that,

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

and applied to my tree with the above fixes.

> +
> +The Hue area setup must match one of the following constrains:
> +
> +::
> +
> +    0L <= 0U <= 1L <= 1U <= 2L <= 2U <= 3L <= 3U <= 4L <= 4U <= 5L <= 5U
> +
> +::
> +
> +    0U <= 1L <= 1U <= 2L <= 2U <= 3L <= 3U <= 4L <= 4U <= 5L <= 5U <= 0L
> +
> +**Byte Order.**
> +All data is stored in memory in little endian format. Each cell in the
> tables +contains one byte.
> +
> +.. flat-table:: VSP1 HGT Data - (776 bytes)
> +    :header-rows:  2
> +    :stub-columns: 0
> +
> +    * - Offset
> +      - :cspan:`4` Memory
> +    * -
> +      - [31:24]
> +      - [23:16]
> +      - [15:8]
> +      - [7:0]
> +    * - 0
> +      - -
> +      - S max [7:0]
> +      - -
> +      - S min [7:0]
> +    * - 4
> +      - :cspan:`4` S sum [31:0]
> +    * - 8
> +      - :cspan:`4` Histogram bucket (m=0, n=0) [31:0]
> +    * - 12
> +      - :cspan:`4` Histogram bucket (m=0, n=1) [31:0]
> +    * -
> +      - :cspan:`4` ...
> +    * - 132
> +      - :cspan:`4` Histogram bucket (m=0, n=31) [31:0]
> +    * - 136
> +      - :cspan:`4` Histogram bucket (m=1, n=0) [31:0]
> +    * -
> +      - :cspan:`4` ...
> +    * - 264
> +      - :cspan:`4` Histogram bucket (m=2, n=0) [31:0]
> +    * -
> +      - :cspan:`4` ...
> +    * - 392
> +      - :cspan:`4` Histogram bucket (m=3, n=0) [31:0]
> +    * -
> +      - :cspan:`4` ...
> +    * - 520
> +      - :cspan:`4` Histogram bucket (m=4, n=0) [31:0]
> +    * -
> +      - :cspan:`4` ...
> +    * - 648
> +      - :cspan:`4` Histogram bucket (m=5, n=0) [31:0]
> +    * -
> +      - :cspan:`4` ...
> +    * - 772
> +      - :cspan:`4` Histogram bucket (m=5, n=31) [31:0]
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c
> b/drivers/media/v4l2-core/v4l2-ioctl.c index b7f7d5f..f459c4f 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -1259,6 +1259,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
> case V4L2_SDR_FMT_CS14LE:	descr = "Complex S14LE"; break;
>  	case V4L2_SDR_FMT_RU12LE:	descr = "Real U12LE"; break;
>  	case V4L2_META_FMT_VSP1_HGO:	descr = "R-Car VSP1 1-D Histogram"; 
break;
> +	case V4L2_META_FMT_VSP1_HGT:	descr = "R-Car VSP1 2-D Histogram"; 
break;
> 
>  	default:
>  		/* Compressed formats */
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 1dbe52a..c8c046c 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -638,7 +638,8 @@ struct v4l2_pix_format {
>  #define V4L2_SDR_FMT_RU12LE       v4l2_fourcc('R', 'U', '1', '2') /* real
> u12le */
> 
>  /* Meta-data formats */
> -#define V4L2_META_FMT_VSP1_HGO    v4l2_fourcc('V', 'S', 'P', 'H') /* R-Car
> VSP1 Histogram */ +#define V4L2_META_FMT_VSP1_HGO    v4l2_fourcc('V', 'S',
> 'P', 'H') /* R-Car VSP1 1-D Histogram */ +#define V4L2_META_FMT_VSP1_HGT   
> v4l2_fourcc('V', 'S', 'P', 'T') /* R-Car VSP1 2-D Histogram */
> 
>  /* priv field value to indicates that subsequent fields are valid. */
>  #define V4L2_PIX_FMT_PRIV_MAGIC		0xfeedcafe

-- 
Regards,

Laurent Pinchart