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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 42392C369C2 for ; Fri, 25 Apr 2025 08:40:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=SdNELu6tX0o/pi8varqYYzdto6XQxyClf203EBF5FuQ=; b=omMaVQwUfvIS/shvKHXN/b5pG5 4SJZyQsTbwcdpA2H9Vm8n0zAwnONhdCJ/FlqyXO+ywFzDxO1JCK4GP/rOE29fnlmVj3nbGhzmDtDP n7HqG2HnMYerrD85EF4v4N60tTLSEU+8Kx0YSBSHJeAgVde6N7e1LJZczCAANYxvKZBqZL8qwB+Pp UWXL5vVm+e1aXBZQ7XcSDwgvgm6Migw7mPhWl5RFkPBOjF2lBMqEC1NaVysB+362PiRf946qot1DT 2MUE53KvYsLhYppAnYktnn9OnBGVsmp4ONAOncZbRqjcLmSylUe2OKR5G7HAXBojz1Zf/1K+RK2GT F+AhfMtA==; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250425_013835_919574_652137B4 X-CRM114-Status: UNSURE ( 9.78 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Pekka, On 17/04/2025 11:13, Pekka Paalanen wrote: >> My understanding is that the Y-only pixel formats behave in a well >> defined way (or, as well defined as the YUV formats), and there's >> nothing more to add here. Is that right? > > There are two things: > > - Y8 follows COLOR_RANGE property, just like all other YUV formats. > - Y8 implies that Cb and Cr are both neutral (0.0 in nominal values). > > I'd like these explicitly written down, so that they become obvious to > everyone. I suspect either one might be easy to forget when writing > code and taking shortcuts without thinking. I didn't find a suitable place in the docs for this, but would this, in the drm_fourcc.h, be enough: /* * 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. * */ #define DRM_FORMAT_Y8 fourcc_code('G', 'R', 'E', 'Y') /* 8-bit Y-only */ #define DRM_FORMAT_Y10_P32 fourcc_code('Y', 'P', 'A', '4') /* [31:0] x:Y2:Y1:Y0 2:10:10:10 little endian */ Tomi