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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 10C7CC433E0 for ; Mon, 15 Mar 2021 12:00:13 +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 95FC664DD7 for ; Mon, 15 Mar 2021 12:00:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 95FC664DD7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=crapouillou.net 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 4FD4889C9C; Mon, 15 Mar 2021 12:00:09 +0000 (UTC) Received: from aposti.net (aposti.net [89.234.176.197]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6A0D889C9B for ; Mon, 15 Mar 2021 12:00:07 +0000 (UTC) Date: Mon, 15 Mar 2021 11:59:50 +0000 From: Paul Cercueil Subject: Re: [PATCH v2 4/5] drm: Add and export function drm_gem_cma_sync_data To: Thomas Zimmermann Message-Id: In-Reply-To: <9c3c8e15-9e8c-4413-e75b-de989a750954@suse.de> References: <20210307202835.253907-1-paul@crapouillou.net> <20210307202835.253907-5-paul@crapouillou.net> <20210311122846.GC1739082@infradead.org> <9c3c8e15-9e8c-4413-e75b-de989a750954@suse.de> MIME-Version: 1.0 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: David Airlie , linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, Christoph Hellwig , od@zcrc.me, dri-devel@lists.freedesktop.org, Sam Ravnborg Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hi Thomas, Le lun. 15 mars 2021 =E0 8:43, Thomas Zimmermann a = =E9crit : > Hi > = > Am 11.03.21 um 13:33 schrieb Paul Cercueil: >> = >> = >> Le jeu. 11 mars 2021 =E0 12:28, Christoph Hellwig = >> a =7F=E9crit : >>> On Sun, Mar 07, 2021 at 08:28:34PM +0000, Paul Cercueil wrote: >>>> + drm_atomic_for_each_plane_damage(&iter, &clip) { >>>> + for (i =3D 0; i < finfo->num_planes; i++) { >>>> + daddr =3D drm_fb_cma_get_gem_addr(state->fb, state, i); >>>> + >>>> + /* Ignore x1/x2 values, invalidate complete lines */ >>>> + offset =3D clip.y1 * state->fb->pitches[i]; >>>> + >>>> + dma_sync_single_for_device(dev, daddr + offset, >>>> + (clip.y2 - clip.y1) * = >>>> state->fb->pitches[i], >>>> + DMA_TO_DEVICE); >>> = >>> Are these helpers only ever used to transfer data to the device and >>> never from it? If so please clearly document that. >> = >> Yes. In the DRM world, are there cases where we transfer data from = >> the =7Fdevice? I assume these cases are handled by v4l2 instead. > = > Software rendering (i.e., anything wrt dumb buffers) likely reads = > back framebuffer content during blit operations. For devices where = > this is a slow operation (e.g., PCI read) we set struct = > drm_mode_config.prefer_shadow to hint renderers to use shadow = > buffering. This has been brought up a few times already. I answered that in the = cover letter. In my case, *writes* (e.g. dumb memcpy) are also slower = with a write-combine buffer than with a non-coherent buffer + cache = sync. So a shadow buffer does nothing for me. Cheers, -Paul _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel