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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1AA1EC433F5 for ; Wed, 16 Feb 2022 13:46:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234106AbiBPNqp (ORCPT ); Wed, 16 Feb 2022 08:46:45 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:34534 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234105AbiBPNqo (ORCPT ); Wed, 16 Feb 2022 08:46:44 -0500 Received: from mail-yb1-xb2f.google.com (mail-yb1-xb2f.google.com [IPv6:2607:f8b0:4864:20::b2f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E014EF65 for ; Wed, 16 Feb 2022 05:46:30 -0800 (PST) Received: by mail-yb1-xb2f.google.com with SMTP id bt13so6136741ybb.2 for ; Wed, 16 Feb 2022 05:46:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fooishbar-org.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=HmFgTFOaUrdQsLp+zoYLJYAEZzFKWR4iy8oL8R7YJhA=; b=piQF2bXbfQ3jAL9Wl9KHIEI/BE7pYDU1IMut0lIzmEScSrQTTjteMmCEzJpApNZRX4 MiSZndY1LTZdnjzdE1PtqAozUueAsk+eHh1cDep+IbGnB9QWT9qZ4gaC5sqvfGpS3BE9 bR1twOpbY9SOcG8uuHnhoXL91tdBw9gU9UmxqJIwGeWaiNwWUjTkd+EOa9X7qSRiP4Ic m8Zx0IpBhy5xVNK8CZj7uL7qa6SdAHfv0MJRk3F6unvP/KZRr7iVVemKX545Vw1/i6nD UkmckP1LIoEqUm8uWPqlNTOC8MeC8E9tZaCEeo4E97rXfUl6R7bkc7GrBneAs4SoAtK4 JANA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=HmFgTFOaUrdQsLp+zoYLJYAEZzFKWR4iy8oL8R7YJhA=; b=TmuDnbL6e33Yac6BbVgfo+0qliRWGXpJ3DCVWSjzk56EbmmKz5/lBBO/cL1/PlbUT4 0PwsbvXqkh/kRkMAnemV7DZipx22t9T/+qPnn1rKgvwyMIEEv1uyxjbs0gNwc/Ac3vKo p+RV7+wfMulMnFm6OhVG5uM8fl3xFJpxFsSoHZANvKnSdBGjBDrlwx0OEj6u8QPSqlqI fye1nCVD1Yi7OJMGI7KP7FdqwDb0YRB9a94QWSyx+KF7HZkWVC8CzNXdAaOgtoTjjZz4 RCqEPBE4duNYXTL4RMsquhxutQzGowh4t08TA3xjP1vSS62SeXrs7YQ32khH7A8jdIKz yFew== X-Gm-Message-State: AOAM533NunjIsETt3uHtQZl9K+HVisYzInmG5bmDdHEFpVQ5i7Yrr2C3 nff1jPa/JKI+0tuhhXJo+sBj5iwASderC+E9IA+5WA== X-Google-Smtp-Source: ABdhPJwDrfO0XNqq06G1iySq3VTrmWTvdn5Z6vOL0Eb4ZcCuGh6EN5CLGZDUWZYdveKOCjkOHjTGRR1Iq8a+ERSnC3g= X-Received: by 2002:a25:6807:0:b0:61a:79a9:526e with SMTP id d7-20020a256807000000b0061a79a9526emr1995117ybc.376.1645019190069; Wed, 16 Feb 2022 05:46:30 -0800 (PST) MIME-Version: 1.0 References: <20220203082546.3099-1-15330273260@189.cn> <20220203082546.3099-2-15330273260@189.cn> <20220203085851.yqstkfgt4dz7rcnw@houat> <20220209084331.fpq5ng3yuqxmby4q@houat> In-Reply-To: From: Daniel Stone Date: Wed, 16 Feb 2022 13:46:18 +0000 Message-ID: Subject: Re: [PATCH v6 1/3] drm/lsdc: add drm driver for loongson display controller To: Sui Jingfeng <15330273260@189.cn> Cc: Maxime Ripard , Thomas Bogendoerfer , suijingfeng , David Airlie , dri-devel@lists.freedesktop.org, Randy Dunlap , Roland Scheidegger , linux-mips@vger.kernel.org, Krzysztof Kozlowski , linux-kernel@vger.kernel.org, Andrey Zhizhikin , Rob Herring , Dan Carpenter , Sam Ravnborg Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Wed, 9 Feb 2022 at 15:41, Sui Jingfeng <15330273260@189.cn> wrote: > On 2022/2/9 16:43, Maxime Ripard wrote: > > More fundamentally (and this extends to the CMA, caching and VRAM stuff > > you explained above), why can't the driver pick the right decision all > > the time and why would that be under the user control? > > The right decision for ls7a1000 is to use VRAM based helper, But sometimes > we need CMA helper based solution. Because: The PRIME support is lost, use > lsdc with etnaviv is not possible any more. > > Buffer sharing with etnaviv is no longer possible, loongson display controllers > are simple which require scanout buffers to be physically contiguous. Other systems have this limitation, and Mesa's 'kmsro' concept makes this work transparently, as long as your driver can export dmabufs when running in 'VRAM' mode. Cheers, Daniel