From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 94C4CD25B44 for ; Wed, 28 Jan 2026 11:49:46 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id F399F10E2A1; Wed, 28 Jan 2026 11:49:45 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="Ji62Omoq"; dkim-atps=neutral Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by gabe.freedesktop.org (Postfix) with ESMTPS id 5F3B610E2A1 for ; Wed, 28 Jan 2026 11:49:44 +0000 (UTC) Received: from pendragon.ideasonboard.com (2001-14ba-703d-e500--2a1.rev.dnainternet.fi [IPv6:2001:14ba:703d:e500::2a1]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id AE752C6F; Wed, 28 Jan 2026 12:49:05 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1769600945; bh=J5GRkADBM7kHKN0psYa8w2c8cQmmZlbTkq09npe3U8Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Ji62OmoqFXpggqhKXPObU9raamBfIqFvqb8PaDcnivhIVJZqWBp7w5PVnbnYlkc3W 4NznQ3zv+AEP4DgFUva9+LXeYK8sZz1PahE875MELTQRFXhf0Mg5fIB0iOFxlay+sb o6uNTEyS8Uv20bY4Gb1wJKovSTTRAKfP7w+9T++E= Date: Wed, 28 Jan 2026 13:49:41 +0200 From: Laurent Pinchart To: Tomi Valkeinen Cc: Vishal Sagar , Anatoliy Klymenko , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Michal Simek , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Geert Uytterhoeven , Dmitry Baryshkov , Pekka Paalanen , Pekka Paalanen , Dmitry Baryshkov Subject: Re: [PATCH v7 03/11] drm/fourcc: Add DRM_FORMAT_Y8 Message-ID: <20260128114941.GF2558360@killaraus> References: <20251201-xilinx-formats-v7-0-1e1558adfefc@ideasonboard.com> <20251201-xilinx-formats-v7-3-1e1558adfefc@ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20251201-xilinx-formats-v7-3-1e1558adfefc@ideasonboard.com> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hi Tomi, Thank you for the patch. On Mon, Dec 01, 2025 at 02:18:45PM +0200, Tomi Valkeinen wrote: > Add greyscale Y8 format. I would explain here why we need a new format and can't just use DRM_FORMAT_R8. You don't need to convince me, but I think it's important to summarize the rationale should someone later wonder why we introduced this. > Acked-by: Dmitry Baryshkov > Reviewed-by: Pekka Paalanen > Reviewed-by: Vishal Sagar > Signed-off-by: Tomi Valkeinen > --- > drivers/gpu/drm/drm_fourcc.c | 1 + > include/uapi/drm/drm_fourcc.h | 10 ++++++++++ > 2 files changed, 11 insertions(+) > > diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > index b22ef86428a1..a39b9d7a5b62 100644 > --- a/drivers/gpu/drm/drm_fourcc.c > +++ b/drivers/gpu/drm/drm_fourcc.c > @@ -275,6 +275,7 @@ const struct drm_format_info *__drm_format_info(u32 format) > { .format = DRM_FORMAT_YVU422, .depth = 0, .num_planes = 3, .cpp = { 1, 1, 1 }, .hsub = 2, .vsub = 1, .is_yuv = true }, > { .format = DRM_FORMAT_YUV444, .depth = 0, .num_planes = 3, .cpp = { 1, 1, 1 }, .hsub = 1, .vsub = 1, .is_yuv = true }, > { .format = DRM_FORMAT_YVU444, .depth = 0, .num_planes = 3, .cpp = { 1, 1, 1 }, .hsub = 1, .vsub = 1, .is_yuv = true }, > + { .format = DRM_FORMAT_Y8, .depth = 8, .num_planes = 1, .cpp = { 1, 0, 0 }, .hsub = 1, .vsub = 1, .is_yuv = true }, > { .format = DRM_FORMAT_NV12, .depth = 0, .num_planes = 2, .cpp = { 1, 2, 0 }, .hsub = 2, .vsub = 2, .is_yuv = true }, > { .format = DRM_FORMAT_NV21, .depth = 0, .num_planes = 2, .cpp = { 1, 2, 0 }, .hsub = 2, .vsub = 2, .is_yuv = true }, > { .format = DRM_FORMAT_NV16, .depth = 0, .num_planes = 2, .cpp = { 1, 2, 0 }, .hsub = 2, .vsub = 1, .is_yuv = true }, > diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h > index 6c786701238e..5cfc188c4e72 100644 > --- a/include/uapi/drm/drm_fourcc.h > +++ b/include/uapi/drm/drm_fourcc.h > @@ -459,6 +459,16 @@ 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 */ > > +/* > + * Y-only (greyscale) formats > + * > + * The Y-only formats are handled similarly to the YCbCr formats in the display > + * pipeline, with the Cb and Cr implicitly neutral (0.0 in nominal values). This > + * also means that COLOR_RANGE property applies to the Y-only formats. > + * Extra blank line. > + */ > + > +#define DRM_FORMAT_Y8 fourcc_code('G', 'R', 'E', 'Y') /* 8-bit Y-only */ I would have gone for 'Y', '8', ' ', ' ' > > /* > * Format Modifiers: -- Regards, Laurent Pinchart