linux-kernel - Re: [PATCH v2 03/10] drm/fourcc: Add DRM_FORMAT

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Message-ID: <CAMuHMdUMEEuCcmzvet=9sfYzn2_XtSkTgvpHkYz+RALCzHDzfg@mail.gmail.com>
Date: Wed, 15 Jan 2025 11:30:26 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
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>, 
	Laurent Pinchart <laurent.pinchart@...asonboard.com>, Michal Simek <michal.simek@....com>, 
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 03/10] drm/fourcc: Add DRM_FORMAT_Y8

Hi Tomi,

On Wed, Jan 15, 2025 at 10:04 AM Tomi Valkeinen
<tomi.valkeinen@...asonboard.com> wrote:
> Add greyscale Y8 format.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>

Thanks for your patch!

> --- a/include/uapi/drm/drm_fourcc.h
> +++ b/include/uapi/drm/drm_fourcc.h
> @@ -405,6 +405,9 @@ extern "C" {
>  #define DRM_FORMAT_YUV444      fourcc_code('Y', 'U', '2', '4') /* non-subsampled Cb (1) and Cr (2) planes */
>  #define DRM_FORMAT_YVU444      fourcc_code('Y', 'V', '2', '4') /* non-subsampled Cr (1) and Cb (2) planes */
>
> +/* Greyscale formats */
> +
> +#define DRM_FORMAT_Y8          fourcc_code('G', 'R', 'E', 'Y')  /* 8-bit Y-only */

I don't think you need this. We already have:

    /* 8 bpp Red (direct relationship between channel value and brightness) */
    #define DRM_FORMAT_R8           fourcc_code('R', '8', ' ', ' ') /*
[7:0] R */

See also commit 8aba4d30520ed656 ("drm/fourcc: Clarify the meaning of
single-channel "red"").

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds