linux-kernel - Re: [PATCH] drm/fourcc: Add AXBXGXRX106106106106 format

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Date:   Wed, 7 Oct 2020 12:06:34 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Matteo Franchin <matteo.franchin@....com>
Cc:     dri-devel <dri-devel@...ts.freedesktop.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Dave Airlie <airlied@...ux.ie>,
        Brian Starkey <brian.starkey@....com>,
        Liviu Dudau <liviu.dudau@....com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        nd <nd@....com>
Subject: Re: [PATCH] drm/fourcc: Add AXBXGXRX106106106106 format

On Wed, Oct 7, 2020 at 11:29 AM Matteo Franchin <matteo.franchin@....com> wrote:
>
> Add ABGR format with 10-bit components packed in 64-bit per pixel.
> This format can be used to handle
> VK_FORMAT_R10X6G10X6B10X6A10X6_UNORM_4PACK16 on little-endian
> architectures.
>
> Signed-off-by: Matteo Franchin <matteo.franchin@....com>

So is this essentially 16 bit, with the lowest 6 bits in each channel
ignored? What exactly is this used for where the full 16bit format
doesn't work?
-Daniel

> ---
>  drivers/gpu/drm/drm_fourcc.c  | 1 +
>  include/uapi/drm/drm_fourcc.h | 7 +++++++
>  2 files changed, 8 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
> index 722c7ebe4e88..bba03fcb016d 100644
> --- a/drivers/gpu/drm/drm_fourcc.c
> +++ b/drivers/gpu/drm/drm_fourcc.c
> @@ -202,6 +202,7 @@ const struct drm_format_info *__drm_format_info(u32 format)
>                 { .format = DRM_FORMAT_XBGR16161616F,   .depth = 0,  .num_planes = 1, .cpp = { 8, 0, 0 }, .hsub = 1, .vsub = 1 },
>                 { .format = DRM_FORMAT_ARGB16161616F,   .depth = 0,  .num_planes = 1, .cpp = { 8, 0, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true },
>                 { .format = DRM_FORMAT_ABGR16161616F,   .depth = 0,  .num_planes = 1, .cpp = { 8, 0, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true },
> +               { .format = DRM_FORMAT_AXBXGXRX106106106106,    .depth = 0,  .num_planes = 1, .cpp = { 8, 0, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true },
>                 { .format = DRM_FORMAT_RGB888_A8,       .depth = 32, .num_planes = 2, .cpp = { 3, 1, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true },
>                 { .format = DRM_FORMAT_BGR888_A8,       .depth = 32, .num_planes = 2, .cpp = { 3, 1, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true },
>                 { .format = DRM_FORMAT_XRGB8888_A8,     .depth = 32, .num_planes = 2, .cpp = { 4, 1, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true },
> diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
> index 82f327801267..76eedba52b77 100644
> --- a/include/uapi/drm/drm_fourcc.h
> +++ b/include/uapi/drm/drm_fourcc.h
> @@ -155,6 +155,13 @@ extern "C" {
>  #define DRM_FORMAT_ARGB16161616F fourcc_code('A', 'R', '4', 'H') /* [63:0] A:R:G:B 16:16:16:16 little endian */
>  #define DRM_FORMAT_ABGR16161616F fourcc_code('A', 'B', '4', 'H') /* [63:0] A:B:G:R 16:16:16:16 little endian */
>
> +/*
> + * RGBA format with 10-bit components packed in 64-bit per pixel, with 6 bits
> + * of unused padding per component:
> + * [63:0] A:x:B:x:G:x:R:x 10:6:10:6:10:6:10:6 little endian
> + */
> +#define DRM_FORMAT_AXBXGXRX106106106106 fourcc_code('A', 'B', '1', '0')
> +
>  /* packed YCbCr */
>  #define DRM_FORMAT_YUYV                fourcc_code('Y', 'U', 'Y', 'V') /* [31:0] Cr0:Y1:Cb0:Y0 8:8:8:8 little endian */
>  #define DRM_FORMAT_YVYU                fourcc_code('Y', 'V', 'Y', 'U') /* [31:0] Cb0:Y1:Cr0:Y0 8:8:8:8 little endian */
> --
> 2.17.1
>


-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch