From patchwork Fri Jun 26 16:48:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brian Starkey X-Patchwork-Id: 11628027 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E72E5618 for ; Fri, 26 Jun 2020 16:48:19 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id CF31020781 for ; Fri, 26 Jun 2020 16:48:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CF31020781 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A1A356ECDE; Fri, 26 Jun 2020 16:48:17 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by gabe.freedesktop.org (Postfix) with ESMTP id 27FEC6ECDE for ; Fri, 26 Jun 2020 16:48:16 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B60861042; Fri, 26 Jun 2020 09:48:15 -0700 (PDT) Received: from DESKTOP-E1NTVVP.localdomain (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 862933F71E; Fri, 26 Jun 2020 09:48:14 -0700 (PDT) From: Brian Starkey To: dri-devel@lists.freedesktop.org Subject: [PATCH v2] drm: drm_fourcc: Add generic alias for 16_16_TILE modifier Date: Fri, 26 Jun 2020 17:48:00 +0100 Message-Id: <20200626164800.11595-1-brian.starkey@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200626163256.46duuouu6ebvtakw@DESKTOP-E1NTVVP.localdomain> References: <20200626163256.46duuouu6ebvtakw@DESKTOP-E1NTVVP.localdomain> 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: , Cc: andrzej.p@samsung.com, liviu.dudau@arm.com, matteo.franchin@arm.com MIME-Version: 1.0 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" In cases such as DRM_FORMAT_MOD_SAMSUNG_16_16_TILE, the modifier describes a generic pixel re-ordering which can be applicable to multiple vendors. Define an alias: DRM_FORMAT_MOD_GENERIC_16_16_TILE, which can be used to describe this layout in a vendor-neutral way, and add a comment about the expected usage of such "generic" modifiers. Changes in v2: - Move note about future cases to comment (Daniel) Signed-off-by: Brian Starkey Reviewed-by: Daniel Vetter --- include/uapi/drm/drm_fourcc.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h index 299f9ac4840b..cb3db4a21012 100644 --- a/include/uapi/drm/drm_fourcc.h +++ b/include/uapi/drm/drm_fourcc.h @@ -345,8 +345,33 @@ extern "C" { * When adding a new token please document the layout with a code comment, * similar to the fourcc codes above. drm_fourcc.h is considered the * authoritative source for all of these. + * + * Generic modifier names: + * + * DRM_FORMAT_MOD_GENERIC_* definitions are used to provide vendor-neutral names + * for layouts which are common across multiple vendors. To preserve + * compatibility, in cases where a vendor-specific definition already exists and + * a generic name for it is desired, the common name is a purely symbolic alias + * and must use the same numerical value as the original definition. + * + * Note that generic names should only be used for modifiers which describe + * generic layouts (such as pixel re-ordering), which may have + * independently-developed support across multiple vendors. + * + * In future cases where a generic layout is identified before merging with a + * vendor-specific modifier, a new 'GENERIC' vendor or modifier using vendor + * 'NONE' could be considered. This should only be for obvious, exceptional + * cases to avoid polluting the 'GENERIC' namespace with modifiers which only + * apply to a single vendor. + * + * Generic names should not be used for cases where multiple hardware vendors + * have implementations of the same standardised compression scheme (such as + * AFBC). In those cases, all implementations should use the same format + * modifier(s), reflecting the vendor of the standard. */ +#define DRM_FORMAT_MOD_GENERIC_16_16_TILE DRM_FORMAT_MOD_SAMSUNG_16_16_TILE + /* * Invalid Modifier *