From patchwork Fri Jul 7 22:40:59 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Andr=C3=A9_Almeida?= X-Patchwork-Id: 117327 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:9f45:0:b0:3ea:f831:8777 with SMTP id v5csp3588947vqx; Fri, 7 Jul 2023 16:04:19 -0700 (PDT) X-Google-Smtp-Source: APBJJlH2LRHlA04fL1AiK3oyBGN8X7I/mLdbeO9zbQUbfCG9QcjLdJeZXGDfAOmAMlIvArf+duKm X-Received: by 2002:a05:6402:31f0:b0:51e:2e39:9003 with SMTP id dy16-20020a05640231f000b0051e2e399003mr4039154edb.40.1688771059465; Fri, 07 Jul 2023 16:04:19 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1688771059; cv=none; d=google.com; s=arc-20160816; b=TOhJLU5LBjYMiC76MydOZcZzSaI0uEBvaP6R6STvJtIMDheP2Em2CJ8FM4FCJOe6rz xP6XoxvmRS276Y2aLy1Jb62zqUiHuBrMq0PSNoRdT7hHpb7JgELOO7EYlvOO/C4L9BMb PHfy9IwXr0ER3+5r8dENQa2PVnfnN7b4wxXys0MZU6M9spIBLEBNvbsZ79eLtfdX5WFl 471mj1zo6GHFoXalhClBIgh6gDcfbVeF1aNzQKae/vTTfQDsi1lKDG2lOAHNX7qP+r0m 8GsO/DIMi+DXyTgu/044nsOoaK+bBdZtGXwUbffQu+bvoVFUDXnGfVDiKSKbVa1fHtax 3J1g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=ILhK3ntOSguFvvoL3dtIQ/0orxl4TRRaxUfEny2T4hQ=; fh=LjT+njuVizWTSzr6iuglUnPxawOqQbLOR7Ym8u+3GU0=; b=BxsCeHOSZlNjj0xX6oP0dJcVA7MI1R3B43PURX6kWlV4g4KWZOq3XVy8Podcq5EuqB 7PpIAneFaq9RK17gmtcntYcbpacjNMnwWGzS2VHtqEJr6HDWn7N5gt18VTJWSg28s7pr 74U1xG8z95f+hdZiMyxQroftyzSV2GnGekw4U0mb5NRbx71Q0aJyAJr4a23TReFpRPXG FZmKJRiSrkzfiSOO2+cEvSCgHSD5k/7Y1e51ffWiRi+bRdQ7eHZWzxAWiDbTr8WQqXO3 ITSsHjXVO+XyM86MBVzBqaQsVkwNGEr+x+HUYySlcHTfKP8wAawWZpqXC8tvpvuhOQHf YHWA== ARC-Authentication-Results: i=1; mx.google.com; dkim=fail header.i=@igalia.com header.s=20170329 header.b="luAS5a/o"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id l19-20020a056402029300b0051e1b797279si2838947edv.166.2023.07.07.16.03.55; Fri, 07 Jul 2023 16:04:19 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=fail header.i=@igalia.com header.s=20170329 header.b="luAS5a/o"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232560AbjGGWmI (ORCPT + 99 others); Fri, 7 Jul 2023 18:42:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232505AbjGGWlx (ORCPT ); Fri, 7 Jul 2023 18:41:53 -0400 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 364C826BC for ; Fri, 7 Jul 2023 15:41:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:MIME-Version:References: In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=ILhK3ntOSguFvvoL3dtIQ/0orxl4TRRaxUfEny2T4hQ=; b=luAS5a/ov3Z7w1pwXMMISdcq0X CmkBLudpjLqOfv+LJLAAHgZSMAOwntplymB5St0mZV6gheeahYHsf0oKk1dEbckva2adI1sAtldg0 zSAfkyB5qESAnGy93JB4hhHc7vEiAIq1eGRa5uuHhV8Ye1zRG/hGSONknqFrN7KJDUsh41ixqVhCn 7pEMfWtuB6/0Rb4vY44mVDt1yIc9YleiwG15e+Ed80YgxVvmPu+KiZZx1W017yqrMNixeQtYjnRJr 5oOG8jA6fnQ2CMTbxf5k92qZOx0ViYm1r5jHbNCXCuZSKJ8sQ4SM5777oDp3S9kiK0I4V0eDj8DvU bbpZeGCQ==; Received: from [187.74.70.209] (helo=steammachine.lan) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1qHu8z-00AP6e-SZ; Sat, 08 Jul 2023 00:41:42 +0200 From: =?utf-8?q?Andr=C3=A9_Almeida?= To: dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, wayland-devel@lists.freedesktop.org Cc: kernel-dev@igalia.com, alexander.deucher@amd.com, christian.koenig@amd.com, pierre-eric.pelloux-prayer@amd.com, Simon Ser , Rob Clark , Pekka Paalanen , Daniel Vetter , Daniel Stone , =?utf-8?b?J01hcmVrIE9sxaHDoWsn?= , Dave Airlie , =?utf-8?q?Michel_D=C3=A4nzer?= , Randy Dunlap , hwentlan@amd.com, joshua@froggi.es, ville.syrjala@linux.intel.com, Pekka Paalanen , =?utf-8?q?Andr=C3=A9_Almeida?= Subject: [PATCH v5 6/6] drm/doc: Define KMS atomic state set Date: Fri, 7 Jul 2023 19:40:59 -0300 Message-ID: <20230707224059.305474-7-andrealmeid@igalia.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230707224059.305474-1-andrealmeid@igalia.com> References: <20230707224059.305474-1-andrealmeid@igalia.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1770804802215675514?= X-GMAIL-MSGID: =?utf-8?q?1770804802215675514?= From: Pekka Paalanen Specify how the atomic state is maintained between userspace and kernel, plus the special case for async flips. Signed-off-by: Pekka Paalanen Signed-off-by: André Almeida Acked-by: Pekka Paalanen Reviewed-by: Daniel Vetter --- v4: total rework by Pekka --- Documentation/gpu/drm-uapi.rst | 41 ++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/Documentation/gpu/drm-uapi.rst b/Documentation/gpu/drm-uapi.rst index 65fb3036a580..6a1662c08901 100644 --- a/Documentation/gpu/drm-uapi.rst +++ b/Documentation/gpu/drm-uapi.rst @@ -486,3 +486,44 @@ and the CRTC index is its position in this array. .. kernel-doc:: include/uapi/drm/drm_mode.h :internal: + +KMS atomic state +================ + +An atomic commit can change multiple KMS properties in an atomic fashion, +without ever applying intermediate or partial state changes. Either the whole +commit succeeds or fails, and it will never be applied partially. This is the +fundamental improvement of the atomic API over the older non-atomic API which is +referred to as the "legacy API". Applying intermediate state could unexpectedly +fail, cause visible glitches, or delay reaching the final state. + +An atomic commit can be flagged with DRM_MODE_ATOMIC_TEST_ONLY, which means the +complete state change is validated but not applied. Userspace should use this +flag to validate any state change before asking to apply it. If validation fails +for any reason, userspace should attempt to fall back to another, perhaps +simpler, final state. This allows userspace to probe for various configurations +without causing visible glitches on screen and without the need to undo a +probing change. + +The changes recorded in an atomic commit apply on top the current KMS state in +the kernel. Hence, the complete new KMS state is the complete old KMS state with +the committed property settings done on top. The kernel will automatically avoid +no-operation changes, so it is safe and even expected for userspace to send +redundant property settings. No-operation changes do not count towards actually +needed changes, e.g. setting MODE_ID to a different blob with identical +contents as the current KMS state shall not be a modeset on its own. + +A "modeset" is a change in KMS state that might enable, disable, or temporarily +disrupt the emitted video signal, possibly causing visible glitches on screen. A +modeset may also take considerably more time to complete than other kinds of +changes, and the video sink might also need time to adapt to the new signal +properties. Therefore a modeset must be explicitly allowed with the flag +DRM_MODE_ATOMIC_ALLOW_MODESET. This in combination with +DRM_MODE_ATOMIC_TEST_ONLY allows userspace to determine if a state change is +likely to cause visible disruption on screen and avoid such changes when end +users do not expect them. + +An atomic commit with the flag DRM_MODE_PAGE_FLIP_ASYNC is allowed to +effectively change only the FB_ID property on any planes. No-operation changes +are ignored as always. Changing any other property will cause the commit to be +rejected.