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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A08A7C41513 for ; Mon, 16 Oct 2023 13:42:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234025AbjJPNms (ORCPT ); Mon, 16 Oct 2023 09:42:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53656 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233922AbjJPNmn (ORCPT ); Mon, 16 Oct 2023 09:42:43 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95CA4116 for ; Mon, 16 Oct 2023 06:42:34 -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:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID: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=tjTgz1VkpWE559Ez4CDuqjmTeXO6YdCAzREG3dFcRbc=; b=sPjwPdYG/qYajZWGp/l9e5Vsew oyu6/2EQaQyVkjQ2CjcnZxghcqawjx4Rg/sgyfZVhre/fFbG5r4u6AblXA//srP5DJO3/dYPKRFsl kCefoElgf051VduuQ3I5wUWDS4Mc/4yvfFCO5Eh/TiX8yLI5ctnRJ6NuqX5hX57hUSyfSxcKbJCwa Eenvq4v8RiVqLZycUHL3lla97mmPPBmC7Am9S9ALZsBMmHI4zlHVh77rlGmjTkSQnEJN0346qdn/d jmn5Oj1Fv5Jsy0jXv/hCE/jsHl7Q+IOq7VIPGJrilTV4ZLLgQ3uSmrqFAofB/gFQAtWEWfKHVUcFi 8kpYgIRA==; Received: from [192.168.12.174] by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_128_GCM:128) (Exim) id 1qsNrN-0014in-7U; Mon, 16 Oct 2023 15:42:17 +0200 Message-ID: Date: Mon, 16 Oct 2023 15:42:16 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 6/6] drm/doc: Define KMS atomic state set Content-Language: en-US To: Pekka Paalanen Cc: =?UTF-8?Q?Michel_D=C3=A4nzer?= , xaver.hugl@gmail.com, pierre-eric.pelloux-prayer@amd.com, Daniel Vetter , =?UTF-8?B?J01hcmVrIE9sxaHDoWsn?= , Randy Dunlap , Daniel Stone , linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, hwentlan@amd.com, Rob Clark , ville.syrjala@linux.intel.com, kernel-dev@igalia.com, alexander.deucher@amd.com, Dave Airlie , christian.koenig@amd.com, joshua@froggi.es, wayland-devel@lists.freedesktop.org References: <20230815185710.159779-1-andrealmeid@igalia.com> <20230815185710.159779-7-andrealmeid@igalia.com> <1b23576d-1649-ff5c-6273-b54729ea46d8@mailbox.org> <20231016151856.74af9305@eldfell> From: =?UTF-8?Q?Andr=C3=A9_Almeida?= In-Reply-To: <20231016151856.74af9305@eldfell> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Pekka, On 10/16/23 14:18, Pekka Paalanen wrote: > On Mon, 16 Oct 2023 12:52:32 +0200 > André Almeida wrote: > >> Hi Michel, >> >> On 8/17/23 12:37, Michel Dänzer wrote: >>> On 8/15/23 20:57, André Almeida wrote: >>>> 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 >>> [...] >>> >>>> +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. [...] >>> During the hackfest in Brno, it was mentioned that a commit which re-sets the same FB_ID could actually have an effect with VRR: It could trigger scanout of the next frame before vertical blank has reached its maximum duration. Some kind of mechanism is required for this in order to allow user space to perform low frame rate compensation. >>> >> Xaver tested this hypothesis in a flipping the same fb in a VRR monitor >> and it worked as expected, so this shouldn't be a concern. > Right, so it must have some effect. It cannot be simply ignored like in > the proposed doc wording. Do we special-case re-setting the same FB_ID > as "not a no-op" or "not ignored" or some other way? There's an effect in the refresh rate, the image won't change but it will report that a flip had happened asynchronously so the reported framerate will be increased. Maybe an additional wording could be like: Flipping to the same FB_ID will result in a immediate flip as if it was changing to a different one, with no effect on the image but effecting the reported frame rate. > > Thanks, > pq