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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 588B8C2F420 for ; Mon, 21 Jan 2019 15:07:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0ED9B20823 for ; Mon, 21 Jan 2019 15:07:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="aVYYgK+H" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729856AbfAUPHh (ORCPT ); Mon, 21 Jan 2019 10:07:37 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:49262 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729072AbfAUPHh (ORCPT ); Mon, 21 Jan 2019 10:07:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=2j5QAMnWZYAHmPB6B/PLFycemJfuLetLmqnb8Ek7zWQ=; b=aVYYgK+HBuEyNiRsC+xcgmMGG BrXscf3Dz0SZfcuB6oOpJWcJmSYnuBHFr79JIiV4zOjYcLMSzLb6fuyNcFPRKJjlFAJIKmQOJrGSl O0f/V84aHAqhGSvfYeaP+MC0tlEqUajjWXCV2qp/FTXI97jI/NWM0NIxR+Qywagl568xIzb1e1YkU uIilgow675PlyDGRpv1MwbLPAXNPusKtP1fJ8J55IkFaXlZyJGlBs4gKretnrvW6Zezlqum5Cr/ya IHzum9uV51KRS2hqSDS5Pr5q1po6+w5iHUUylPvBRXC/eGGw0wIEKIulX+5BYDKtUvkAqvbmL4Msm /7kd3RPsQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1glbAk-00015z-Kc; Mon, 21 Jan 2019 15:07:34 +0000 Date: Mon, 21 Jan 2019 07:07:34 -0800 From: Christoph Hellwig To: Ard Biesheuvel Cc: linux-arm-kernel@lists.infradead.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, Christian Koenig , Alex Deucher , David Zhou , Huang Rui , Junwei Zhang , Michel Daenzer , David Airlie , Daniel Vetter , Maarten Lankhorst , Maxime Ripard , Sean Paul , Michael Ellerman , Benjamin Herrenschmidt , Will Deacon Subject: Re: [RFC PATCH] drm: disable WC optimization for cache coherent devices on non-x86 Message-ID: <20190121150734.GA30582@infradead.org> References: <20190121100617.2311-1-ard.biesheuvel@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190121100617.2311-1-ard.biesheuvel@linaro.org> User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > +#include This header is not for usage in device drivers, but purely for dma-mapping implementations! > +static inline bool drm_device_can_wc_memory(struct drm_device *ddev) > { > + if (IS_ENABLED(CONFIG_PPC)) > + return IS_ENABLED(CONFIG_NOT_COHERENT_CACHE); > + else if (IS_ENABLED(CONFIG_MIPS)) > + return !IS_ENABLED(CONFIG_CPU_LOONGSON3); > + else if (IS_ENABLED(CONFIG_X86)) > + return true; > + > + return !dev_is_dma_coherent(ddev->dev); And even if something like this was valid to do, it would have to be a core function with an arch hook, and not hidden in a random driver.