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 35B02C433E4 for ; Fri, 10 Jul 2020 20:02:35 +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 065C52075D for ; Fri, 10 Jul 2020 20:02:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="SqNPnTQb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 065C52075D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch 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 8C2556ED02; Fri, 10 Jul 2020 20:02:33 +0000 (UTC) Received: from mail-oi1-x243.google.com (mail-oi1-x243.google.com [IPv6:2607:f8b0:4864:20::243]) by gabe.freedesktop.org (Postfix) with ESMTPS id B3CA66E175 for ; Fri, 10 Jul 2020 20:02:32 +0000 (UTC) Received: by mail-oi1-x243.google.com with SMTP id w17so5760136oie.6 for ; Fri, 10 Jul 2020 13:02:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=hlzdQKgtPmO74k0pNR7vHuIZBrt/Pc63RtVTndWe5dA=; b=SqNPnTQbjsymEOAYWvf7HTkD0FI+HW6j/e6KRe6XGJh3lSuGZ0C7kP/iBUFjVJ03M5 t8w6HTmvlfEqaW7ZR4/WDh2zFfGdT+tuiUcDAyD+AEP04wFuCMGfRQQM26yq17Soms89 nnpW0b1zmvAznK5+R6nx5wurVKlahUyCP/oLY= 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=hlzdQKgtPmO74k0pNR7vHuIZBrt/Pc63RtVTndWe5dA=; b=JsiTOZOQ1KB9N6I4VMjius9XvljR1bVHVBKQezQfMquXgeCmRfZi5WueomuQ+LfA6O LASqAm+CsjYYNJ0XF/9Wb3LlQmcx/AWCTOsSgjTu4lwhJnRHLiBdZG8j7y5RxiGwKmcV 3OW/tfD7dWiWv8oNe6zeCEIouHC1C1Igi3QUoiz6dRVIYhSOvTPfAxubcwBNiaoSb0aZ kQLm4rMDT9HT6B0I9SvQh3Gyayg0GK++mGMvlH2WqSm6zU0HnKy/Gi/GX0GQ19pUSp3B Enw/UZiYUY4fks9jaBQbTT1u+DETAr1WF94Vl1rJ/Ba1sZ6Clpl/Bvb7/9k6Fyh3StyB hrng== X-Gm-Message-State: AOAM530BE3hoxcOoOw8db/HyeAEx1VOrtjeFfF87xhm5fKZoXDlMzjVN ZKmuzK2ioMkCdo1Hsbxl95eereInssd7djWnLr6ERERW X-Google-Smtp-Source: ABdhPJyXe/UuJLRx5f5TlPpv/BPhnkWHORX2InNLi0AlJObIla3gh+GkiBljOI27Z+bfXCvGSQK4tsearkrRp5oifn8= X-Received: by 2002:aca:da03:: with SMTP id r3mr5553679oig.14.1594411351996; Fri, 10 Jul 2020 13:02:31 -0700 (PDT) MIME-Version: 1.0 References: <20200707201229.472834-1-daniel.vetter@ffwll.ch> <20200707201229.472834-3-daniel.vetter@ffwll.ch> <20200709080911.GP3278063@phenom.ffwll.local> <20200710124357.GB23821@mellanox.com> <5c163d74-4a28-1d74-be86-099b4729a2e0@amd.com> <20200710125453.GC23821@mellanox.com> <4f4a2cf7-f505-8494-1461-bd467870481e@amd.com> <20200710134826.GD23821@mellanox.com> <20200710142347.GE23821@mellanox.com> In-Reply-To: <20200710142347.GE23821@mellanox.com> From: Daniel Vetter Date: Fri, 10 Jul 2020 22:02:20 +0200 Message-ID: Subject: Re: [PATCH 02/25] dma-fence: prime lockdep annotations To: Jason Gunthorpe 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: Chris Wilson , kernel test robot , linux-rdma , Felix Kuehling , DRI Development , =?UTF-8?Q?Christian_K=C3=B6nig?= , "moderated list:DMA BUFFER SHARING FRAMEWORK" , =?UTF-8?Q?Thomas_Hellstr=C3=B6m?= , amd-gfx list , Daniel Vetter , "open list:DMA BUFFER SHARING FRAMEWORK" , Intel Graphics Development , Mika Kuoppala Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Fri, Jul 10, 2020 at 4:23 PM Jason Gunthorpe wrote: > > On Fri, Jul 10, 2020 at 04:02:35PM +0200, Daniel Vetter wrote: > > > > dma_fence only possibly makes some sense if you intend to expose the > > > completion outside a single driver. > > > > > > The prefered kernel design pattern for this is to connect things with > > > a function callback. > > > > > > So the actual use case of dma_fence is quite narrow and tightly linked > > > to DRM. > > > > > > I don't think we should spread this beyond DRM, I can't see a reason. > > > > Yeah v4l has a legit reason to use dma_fence, android wants that > > there. > > 'legit' in the sense the v4l is supposed to trigger stuff in DRM when > V4L DMA completes? I would still see that as part of DRM Yes, and also the other way around. But thus far it didn't land. -Daniel > Or is it building a parallel DRM like DMA completion graph? > > > > Trying to improve performance of limited HW by using sketchy > > > techniques at the cost of general system stability should be a NAK. > > > > Well that's pretty much gpu drivers, all the horrors for a bit more speed :-) > > > > On the text itself, should I upgrade to "must not" instead of "should > > not"? Or more needed? > > Fundamentally having some unknowable graph of dependencies where parts > of the graph can be placed in critical regions like notifiers is a > complete maintenance nightmare. > > I think building systems like this should be discouraged :\ -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel