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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 62A12C6FD1D for ; Fri, 17 Mar 2023 11:47:20 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8453610E105; Fri, 17 Mar 2023 11:47:19 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3BCF310E0F6 for ; Fri, 17 Mar 2023 11:47:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1679053635; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=hI3L9hrAihHETIeCxDjASUcWbVB3+GqPGjTZpo1htfw=; b=h8MuODO5QHp69t9b1gTEVEnsCeyvV3/B8P2hjeaL/oog2EUVGzVRMhn6EDs0qZGYLaskWq j95T6sTistKRK795XgrRKQHtDMNv6Nt+lamYcUN0SmA0wxV2xlgVRwhoHb4n9VN2EweplT Ck/le9Sfdd6NYLKXB5IUP7sxSHqqWZc= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-298-I-MqAbIpNZCdAMtTCvlh7A-1; Fri, 17 Mar 2023 07:47:11 -0400 X-MC-Unique: I-MqAbIpNZCdAMtTCvlh7A-1 Received: by mail-wm1-f69.google.com with SMTP id j36-20020a05600c1c2400b003ed245a452fso2157603wms.3 for ; Fri, 17 Mar 2023 04:47:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679053630; h=mime-version:message-id:date:references:in-reply-to:subject:cc:to :from:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=hI3L9hrAihHETIeCxDjASUcWbVB3+GqPGjTZpo1htfw=; b=L7o+ThJ4vX4bvVOYYr0AF8X/VTETF3r48sBQNouS0HLvKnBubu4rtnidOPkSCpEnl8 vUoxBAUIhzTMiBqUy6mGeh4CKxunVjeMl8b3qvIXAgLGUPBvTi/dNUP1eAn1bAUC+h7s 8t78yVKFFTL5NegCNafu7cnuVyT8yhriU3pCuKNKXeYd5d6dI2NxXZXVLGwTR1p51Phf MU5iBbLWVk9bOOEFJ4dXT5eNhO1QmIPkuhWfwmqusargBnMCb9BHoBWVWRE/wBqQvOBb A+uFJZGIGUwPFCFMsPmpl2FQG1bqFS4EFH3s/DzceM97yRf22NvQsLjC5qMxokIHBmKP xIWA== X-Gm-Message-State: AO0yUKXdWbd9ZJo9d20K2DH9lbaByEoRjzc1HLFt2Pa9mM/DJLJCora/ 0yQvx627L/1svW92hftPYS/vuUE7FymkcC0n1+XIksCwkovg/prjUhQ1dQocGJCRHLlN6c75EY3 MynBlGxZsn2NtVxCZWEqxXgMovY6n X-Received: by 2002:adf:f7cc:0:b0:2cf:f3e8:910d with SMTP id a12-20020adff7cc000000b002cff3e8910dmr6935642wrq.16.1679053630759; Fri, 17 Mar 2023 04:47:10 -0700 (PDT) X-Google-Smtp-Source: AK7set+8+jG8RXJ2I6fuXcx2nwI3HbsZkah9pNnMvXVftlA/SCG04uNXuT/TtBoE9UdSQBFAyf4ppw== X-Received: by 2002:adf:f7cc:0:b0:2cf:f3e8:910d with SMTP id a12-20020adff7cc000000b002cff3e8910dmr6935635wrq.16.1679053630497; Fri, 17 Mar 2023 04:47:10 -0700 (PDT) Received: from localhost (205.pool92-176-231.dynamic.orange.es. [92.176.231.205]) by smtp.gmail.com with ESMTPSA id y16-20020a056000109000b002c56013c07fsm1745540wrw.109.2023.03.17.04.47.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 Mar 2023 04:47:10 -0700 (PDT) From: Javier Martinez Canillas To: Thomas Zimmermann , daniel@ffwll.ch, airlied@gmail.com, mripard@kernel.org, maarten.lankhorst@linux.intel.com, zackr@vmware.com, kraxel@redhat.com, dri-devel@lists.freedesktop.org, virtualization@lists.linux-foundation.org, linux-graphics-maintainer@vmware.com Subject: Re: [PATCH 1/6] drm/fbdev-generic: Always use shadow buffering In-Reply-To: <20230315161442.27318-2-tzimmermann@suse.de> References: <20230315161442.27318-1-tzimmermann@suse.de> <20230315161442.27318-2-tzimmermann@suse.de> Date: Fri, 17 Mar 2023 12:47:08 +0100 Message-ID: <871qlnr45f.fsf@minerva.mail-host-address-is-not-set> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain 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: Thomas Zimmermann Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Thomas Zimmermann writes: Hello Thomas, > Remove all codepaths that implement fbdev output directly on GEM > buffers. Always allocate a shadow buffer in system memory and set > up deferred I/O for mmap. > > The fbdev code that operated directly on GEM buffers was used by > drivers based on GEM DMA helpers. Those drivers have been migrated > to use fbdev-dma, a dedicated fbdev emulation for DMA memory. All > remaining users of fbdev-generic require shadow buffering. > > Memory management of the remaining callers uses TTM, GEM SHMEM > helpers or a variant of GEM DMA helpers that is incompatible with > fbdev-dma. Therefore remove the unused codepaths from fbdev-generic > and simplify the code. > > Using a shadow buffer with deferred I/O is probably the best case > for most remaining callers. Some of the TTM-based drivers might > benefit from a dedicated fbdev emulation that operates directly on > the driver's video memory. > But it's questionable if that would be useful due the limited ammount of video memory that most of the devices using TTM-based drivers have, right? > Signed-off-by: Thomas Zimmermann > --- It's much cleaner indeed to have fbdev-dma separated from fbdev-generic. Reviewed-by: Javier Martinez Canillas -- Best regards, Javier Martinez Canillas Core Platforms Red Hat