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 X-Spam-Level: X-Spam-Status: No, score=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1D4D6C433B4 for ; Fri, 21 May 2021 12:22:55 +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 7C7B1613BF for ; Fri, 21 May 2021 12:22:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7C7B1613BF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=fooishbar.org 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 CFBE06E18E; Fri, 21 May 2021 12:22:53 +0000 (UTC) Received: from mail-wr1-x42a.google.com (mail-wr1-x42a.google.com [IPv6:2a00:1450:4864:20::42a]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0E1466E49B for ; Fri, 21 May 2021 12:22:53 +0000 (UTC) Received: by mail-wr1-x42a.google.com with SMTP id z17so20867042wrq.7 for ; Fri, 21 May 2021 05:22:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fooishbar-org.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=tXzqoTh9Q6otGWSG/m2z4V/r+EdDHQXeOAwek5k1Apw=; b=fhGWDMtRWPPjaQRts6ngbU7RFDRPLZxsO/dYPBecxs11qDVpGOrqwFwTAclyPM2NM3 nJP9nH1WfXkimY2pRXSwkgLLRAM1hH5iq2wdhk6yXFysmb/2V3dCMD+m/r8bCg5pCu20 ytbeUFu8HYocl8xDkZD07SCx8OTWunCSNaeGb5HErEc3xvmS5tCcs72NgEZ5msvLwMmJ TOWwwzflosPbtN0ZPrkoNPsHKONhitwQCzjd2zYdQDaHymQK32IP8XUOxG5tKCfgtJrg sUALcf4OR6cFiuK4C+tykpV7nmZrJeviPP7dL+Zbes4wNiRGNZImMKgqKoXmpnF0BBeO sm8A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=tXzqoTh9Q6otGWSG/m2z4V/r+EdDHQXeOAwek5k1Apw=; b=O2rC6ym2tW1Sw3gb3mIPEY8g7ov6ELCqddZ2rguGTmIEzqYLFS5HS+Msso4Ho3TgZA 97VdGIXd7dKuMo0j07GqlM3i+5mlGIFhU/zfiJ1OApb7Zn284Ot9y6WoXiC24nuvEJiv gcwybF/pYz+rBTXSkSKJvO5afG58vzfhL8GNsCfcYZ7pNieG1K/qH4xbLY11K4rsZUry 3rqscyzhAJS2N9u5UkpGjfbGZ2f5M5lZGE6dNkcc/eIIOhlzbNg0EQqhmK6dsFz38NE4 vmgLg09eg5SDy6IYlicMzN/DOY+sCpa7zO0D/erNvDChpPg9qHw8ASXPoUPtou8rA+Kd IA8Q== X-Gm-Message-State: AOAM533h1SrPImm3S4tpEZuHFDY8yh20G+eMdAFJzL9+MDTlPgRn10ca v6+H84va/C8D/A6GVU8jhcZAip86jumiAbWHdzWGTw== X-Google-Smtp-Source: ABdhPJzs6JDh/PVfFHAZiz0tvGCOrZlKRQmwz7h15e9g9pD1J/vW4gLLdrMc8KrEGPgbhOVJa3TJluupr6PSsDmH+Fc= X-Received: by 2002:adf:e70e:: with SMTP id c14mr9371714wrm.6.1621599771623; Fri, 21 May 2021 05:22:51 -0700 (PDT) MIME-Version: 1.0 References: <20210521090959.1663703-1-daniel.vetter@ffwll.ch> <20210521090959.1663703-4-daniel.vetter@ffwll.ch> In-Reply-To: <20210521090959.1663703-4-daniel.vetter@ffwll.ch> From: Daniel Stone Date: Fri, 21 May 2021 13:22:40 +0100 Message-ID: Subject: Re: [PATCH 04/11] drm/panfrost: Fix implicit sync To: Daniel Vetter Content-Type: text/plain; charset="UTF-8" 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: Tomeu Vizoso , Intel Graphics Development , DRI Development , Steven Price , "moderated list:DMA BUFFER SHARING FRAMEWORK" , Alyssa Rosenzweig , Daniel Vetter , =?UTF-8?Q?Christian_K=C3=B6nig?= , "open list:DMA BUFFER SHARING FRAMEWORK" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hi, On Fri, 21 May 2021 at 10:10, Daniel Vetter wrote: > Currently this has no practial relevance I think because there's not > many who can pull off a setup with panfrost and another gpu in the > same system. But the rules are that if you're setting an exclusive > fence, indicating a gpu write access in the implicit fencing system, > then you need to wait for all fences, not just the previous exclusive > fence. > > panfrost against itself has no problem, because it always sets the > exclusive fence (but that's probably something that will need to be > fixed for vulkan and/or multi-engine gpus, or you'll suffer badly). > Also no problem with that against display. Yeah, the 'second-generation Valhall' GPUs coming later this year / early next year are starting to get pretty weird. Firmware-mediated job scheduling out of multiple queues, userspace having direct access to the queues and can do inter-queue synchronisation (at least I think so), etc. For bonus points, synchronisation is based on $addr = $val to signal and $addr == $val to wait, with a separate fence primitive as well. Obviously Arm should be part of this conversation here, but I guess we'll have to wait for a while yet to see how everything's shaken out with this new gen, and hope that whatever's been designed upstream in the meantime is actually vaguely compatible ... Cheers, Daniel