linux-kernel - Re: [PATCH v7 02/11] drm/fourcc: Add DRM_FORMAT

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Message-ID: <20260128122144.GJ2558360@killaraus>
Date: Wed, 28 Jan 2026 14:21:44 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Cc: Vishal Sagar <vishal.sagar@....com>,
	Anatoliy Klymenko <anatoliy.klymenko@....com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
	Michal Simek <michal.simek@....com>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
	Pekka Paalanen <ppaalanen@...il.com>,
	Dmitry Baryshkov <lumag@...nel.org>
Subject: Re: [PATCH v7 02/11] drm/fourcc: Add DRM_FORMAT_XV15/XV20

Hi Tomi,

On Mon, Dec 01, 2025 at 02:18:44PM +0200, Tomi Valkeinen wrote:
> Add two new pixel formats:
> 
> DRM_FORMAT_XV15 ("XV15")
> DRM_FORMAT_XV20 ("XV20")
> 
> The formats are 2 plane 10 bit per component YCbCr, with the XV15 2x2
> subsampled whereas XV20 is 2x1 subsampled.
> 
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Reviewed-by: Vishal Sagar <vishal.sagar@....com>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
> ---
>  drivers/gpu/drm/drm_fourcc.c  | 6 ++++++
>  include/uapi/drm/drm_fourcc.h | 8 ++++++++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
> index e662aea9d105..b22ef86428a1 100644
> --- a/drivers/gpu/drm/drm_fourcc.c
> +++ b/drivers/gpu/drm/drm_fourcc.c
> @@ -381,6 +381,12 @@ const struct drm_format_info *__drm_format_info(u32 format)
>  		{ .format = DRM_FORMAT_S416,            .depth = 0,  .num_planes = 3,
>  		  .char_per_block = { 2, 2, 2 }, .block_w = { 1, 1, 1 }, .block_h = { 1, 1, 1 },
>  		  .hsub = 1, .vsub = 1, .is_yuv = true},
> +		{ .format = DRM_FORMAT_XV15,		.depth = 0,  .num_planes = 2,
> +		  .char_per_block = { 4, 8, 0 }, .block_w = { 3, 3, 0 }, .block_h = { 1, 1, 0 },
> +		  .hsub = 2, .vsub = 2, .is_yuv = true },

Given the horizontal subsampling, don't we have 6 pixels in 8 bytes ?

> +		{ .format = DRM_FORMAT_XV20,		.depth = 0,  .num_planes = 2,
> +		  .char_per_block = { 4, 8, 0 }, .block_w = { 3, 3, 0 }, .block_h = { 1, 1, 0 },
> +		  .hsub = 2, .vsub = 1, .is_yuv = true },
>  	};
>  
>  	unsigned int i;
> diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
> index e527b24bd824..6c786701238e 100644
> --- a/include/uapi/drm/drm_fourcc.h
> +++ b/include/uapi/drm/drm_fourcc.h
> @@ -322,6 +322,14 @@ extern "C" {
>  #define DRM_FORMAT_RGB565_A8	fourcc_code('R', '5', 'A', '8')
>  #define DRM_FORMAT_BGR565_A8	fourcc_code('B', '5', 'A', '8')
>  
> +/*
> + * 2 plane 10 bit per component YCrCb
> + * index 0 = Y plane, [31:0] x:Y2:Y1:Y0 2:10:10:10 little endian
> + * index 1 = Cb:Cr plane, [63:0] x:Cr2:Cb2:Cr1:x:Cb1:Cr0:Cb0 2:10:10:10:2:10:10:10 little endian
> + */
> +#define DRM_FORMAT_XV15		fourcc_code('X', 'V', '1', '5') /* 2x2 subsampled Cr:Cb plane 2:10:10:10 */
> +#define DRM_FORMAT_XV20		fourcc_code('X', 'V', '2', '0') /* 2x1 subsampled Cr:Cb plane 2:10:10:10 */
> +
>  /*
>   * 2 plane YCbCr
>   * index 0 = Y plane, [7:0] Y

-- 
Regards,

Laurent Pinchart