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 9CEFAC43461 for ; Fri, 21 May 2021 13:23:52 +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 55803613EC for ; Fri, 21 May 2021 13:23:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 55803613EC 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 A7D166F648; Fri, 21 May 2021 13:23:51 +0000 (UTC) Received: from mail-wr1-x429.google.com (mail-wr1-x429.google.com [IPv6:2a00:1450:4864:20::429]) by gabe.freedesktop.org (Postfix) with ESMTPS id 5495F6F648 for ; Fri, 21 May 2021 13:23:51 +0000 (UTC) Received: by mail-wr1-x429.google.com with SMTP id d11so21049128wrw.8 for ; Fri, 21 May 2021 06:23:51 -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:content-transfer-encoding; bh=zBr2qa8weJ1fN+pyrA9yHt47NZiiPugqQIjjkfzP+jw=; b=Vo39h2GhwMLbJLo+/rJ8jKdDxxx7yt/+DuSYtdRMJYd/ewYSQQsrwCnOCge0+aOIM2 9/KcfjejnPY8GM8mZ7TLh9EDtHEL/1jvG9ThrG9zg8eAz/GKa3MaVPVSMLnA4tV2yryY wubn8HMprLTyeofXBSRountcrg6j1SBLsPKvAsbxcvpmEVW7xAfjiqMlhxwraaQJlRHQ RBb6DN/tULEGgiS/IonVr9QgSxe37CitIuX4+gnFggRx+HHuCHA5loPr60vmuDY9nqZD rfQA3gO4qDA/z8bt5atk4ADkTZhfdIHY0OqxfaTHUZQut/UlgKWx4Let826C6h8Ly2d/ GudQ== 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:content-transfer-encoding; bh=zBr2qa8weJ1fN+pyrA9yHt47NZiiPugqQIjjkfzP+jw=; b=g63rnUzvAQ+AdUwsVl+8Cv/wbLoxHZVtEYg+o/oyLrIeeSwDajviUHP06XBMN25bnt OvXKb7+cScULefjd1nf8nWPqG8h5nkwKKiTLhRrNCq79myDXnozPNg9MlIgG41eXf4Ag CQuy/2WLJCgE/DWqiYKA8PyAj02QoqlaAvaSkB6MlpCNTo+D0Gh+g9OHb/cCsOxSvddt AUoDUZhd9TO3ZCL9sQLgPycnCwZ2xO7R2zDlDosZrBNIJsrDEi2sri6COrw0EMK9xVEj 4wZZsJJ3WKzAk1qTs6CWyEO3mRSiiajrJGCLfsIBV5aE4VzJrXl8kBo1c58RDbl1DT91 QW6A== X-Gm-Message-State: AOAM531sOss8ds3jblY+0XoUexwwMhze+tkn91BshPIcdVeXAAXjTH8L yIvpw4o2zP10/DqzHgF7B1xY0cjoE0K7lMQ8eP8mGA== X-Google-Smtp-Source: ABdhPJyU8TEmXK/S6OXq7q8k124HIgHp5J7hILQzz4PXVCcZY3JiYAj8Ouwu177Y0/InrwMU7WBJIc4BjzJuyR8pTms= X-Received: by 2002:a5d:6e04:: with SMTP id h4mr9422676wrz.256.1621603429939; Fri, 21 May 2021 06:23:49 -0700 (PDT) MIME-Version: 1.0 References: <20210521090959.1663703-1-daniel.vetter@ffwll.ch> <20210521090959.1663703-4-daniel.vetter@ffwll.ch> <39aa30e4-2726-a0ba-3537-3be609dbc0b5@amd.com> In-Reply-To: <39aa30e4-2726-a0ba-3537-3be609dbc0b5@amd.com> From: Daniel Stone Date: Fri, 21 May 2021 14:23:38 +0100 Message-ID: Subject: Re: [Linaro-mm-sig] [PATCH 04/11] drm/panfrost: Fix implicit sync To: =?UTF-8?Q?Christian_K=C3=B6nig?= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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 , Daniel Vetter , Intel Graphics Development , DRI Development , Steven Price , "moderated list:DMA BUFFER SHARING FRAMEWORK" , Alyssa Rosenzweig , Daniel Vetter , "open list:DMA BUFFER SHARING FRAMEWORK" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Fri, 21 May 2021 at 14:09, Christian K=C3=B6nig wrote: > Am 21.05.21 um 14:54 schrieb Daniel Stone: > > If you're curious, the interface definitions are in the csf/ directory > > in the 'Bifrost kernel driver' r30p0 download you can get from the Arm > > developer site. Unfortunately the exact semantics aren't completely > > clear. > > Well it is actually relatively simple. Take a look at the timeline > semaphores from Vulkan, everybody is basically implementing the same > semantics now. > > When you queued up a bunch of commands on your hardware, the first one > will write value 1 to a 64bit memory location, the second one will write > value 2, the third value 3 and so on. After writing the value the > hardware raises and interrupt signal to everybody interested. > > In other words pretty standard memory fence behavior. > > When you now have a second queue which depends on work of the first one > you look at the memory location and do a compare. If you depend on the > third submission you just wait for the value to be >3 and are done. Right, it is clearly defined to the timeline semaphore semantics, I just meant that it's not clear how it works at a lower level wrt the synchronisation and signaling. The simplest possible interpretation is that wait_addrval blocks infinitely before kick-cmdbuf, but that seems painful with only 32 queues. And the same for fences, which are a binary signal. I guess we'll find out. My tooth hurts. Cheers, Daniel