Re: [PATCH v3 4/5] media: Add HEXTILE compressed format

Nicolas Dufresne
2022-05-20T18:43:42Z

Le vendredi 20 mai 2022 à 10:47 +0800, Marvin Lin a écrit :
> Add HEXTILE compressed format. This format is defined in Remote Framebuffer
> Protocol (RFC 6143) and is used by Encoding Compression Engine present on
> Nuvoton NPCM SoCs.

Ah, ancient RFB compression. I also found that there is encoder/decoders part of
FFMPEG and GStreamer VMNC (VMWare CODECs) and also a decoder in GStreamer RFB
plugin. It is though an obsolete format for all of these technology, thanks for
identifying clearly.

Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>

>
> Signed-off-by: Marvin Lin <milkfafa@gmail.com>
> ---
> Documentation/userspace-api/media/v4l/pixfmt-reserved.rst | 7 +++++++
> drivers/media/v4l2-core/v4l2-ioctl.c | 1 +
> include/uapi/linux/videodev2.h | 1 +
> 3 files changed, 9 insertions(+)
>
> diff --git a/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst b/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst
> index cabfa34b7db5..bad2b9a2f16e 100644
> --- a/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst
> +++ b/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst
> @@ -239,6 +239,13 @@ please make a proposal on the linux-media mailing list.
> It remains an opaque intermediate format and the MDP hardware must be
> used to convert ``V4L2_PIX_FMT_MT21C`` to ``V4L2_PIX_FMT_NV12M``,
> ``V4L2_PIX_FMT_YUV420M`` or ``V4L2_PIX_FMT_YVU420``.
> + * .. _V4L2-PIX-FMT-HEXTILE:
> +
> + - ``V4L2_PIX_FMT_HEXTILE``
> + - 'HXTL'
> + - Compressed format used by Nuvoton NPCM video driver. This format is
> + defined in Remote Framebuffer Protocol (RFC 6143, chapter 7.7.4 Hextile
> + Encoding).
> .. raw:: latex
>
> \normalsize
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index 96e307fe3aab..9365519d65bb 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -1441,6 +1441,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
> case V4L2_PIX_FMT_SE401: descr = "GSPCA SE401"; break;
> case V4L2_PIX_FMT_S5C_UYVY_JPG: descr = "S5C73MX interleaved UYVY/JPEG"; break;
> case V4L2_PIX_FMT_MT21C: descr = "Mediatek Compressed Format"; break;
> + case V4L2_PIX_FMT_HEXTILE: descr = "Hextile Compressed Format"; break;
> default:
> if (fmt->description[0])
> return;
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 3768a0a80830..1c7af015b43b 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -746,6 +746,7 @@ struct v4l2_pix_format {
> #define V4L2_PIX_FMT_INZI v4l2_fourcc('I', 'N', 'Z', 'I') /* Intel Planar Greyscale 10-bit and Depth 16-bit */
> #define V4L2_PIX_FMT_CNF4 v4l2_fourcc('C', 'N', 'F', '4') /* Intel 4-bit packed depth confidence information */
> #define V4L2_PIX_FMT_HI240 v4l2_fourcc('H', 'I', '2', '4') /* BTTV 8-bit dithered RGB */
> +#define V4L2_PIX_FMT_HEXTILE v4l2_fourcc('H', 'X', 'T', 'L') /* Hextile compression */
>
> /* 10bit raw bayer packed, 32 bytes for every 25 pixels, last LSB 6 bits unused */
> #define V4L2_PIX_FMT_IPU3_SBGGR10 v4l2_fourcc('i', 'p', '3', 'b') /* IPU3 packed 10-bit BGGR bayer */