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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 5D9B8C43331 for ; Mon, 11 Nov 2019 10:15:41 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 3260E214E0 for ; Mon, 11 Nov 2019 10:15:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Htp9KD08" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3260E214E0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=WnfPndWeX0mUsuAklT2o//R5OYl4xvQ+qR7VAwKKQLU=; b=Htp9KD08uLJaH7 LxojPnyA0TBnOk3rg7RE4tStNrVqiK6G50I+Rptor2uG2pkxJhiGhg/d1DQwpD6U4pGFwNA31Fruh M5RdMoNq8gKMOWPilx4/XLIiGCgMxSmoJWbgTIiaEtI4QAWAZIMfKgZWIJcHngooz2eK8e+inn3yx lhA1bn+BpaJ1cx6vzTZ0N0b3ATwWogoD7B4ZM/XDtwuGo/kaZhqrftynCdkLPiPU5W45ksxWN6szF 7DIIehmrzqsnnrAx744erFJ6Lszwyuo2Wc4jqN/m8ONQX/BVqeitfd2edku8syCdtnTxZdbqU7yBQ RwRQ+UafYuid0SrDNk1w==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iU6jR-0007wp-W4; Mon, 11 Nov 2019 10:15:37 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iU6jO-0007w5-JL; Mon, 11 Nov 2019 10:15:35 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 8B1EE68BE1; Mon, 11 Nov 2019 11:15:31 +0100 (CET) Date: Mon, 11 Nov 2019 11:15:31 +0100 From: Christoph Hellwig To: Arnd Bergmann Subject: Re: [PATCH 10/21] asm-generic: ioremap_uc should behave the same with and without MMU Message-ID: <20191111101531.GA12294@lst.de> References: <20191029064834.23438-1-hch@lst.de> <20191029064834.23438-11-hch@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191111_021534_784127_CBD7C181 X-CRM114-Status: UNSURE ( 9.63 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-ia64@vger.kernel.org, Linux-sh list , "linux-kernel@vger.kernel.org" , Guo Ren , sparclinux , linux-riscv@lists.infradead.org, Vincent Chen , Christoph Hellwig , linux-arch , linux-s390 , "open list:QUALCOMM HEXAGON..." , the arch/x86 maintainers , "open list:SYNOPSYS ARC ARCHITECTURE" , linux-xtensa@linux-xtensa.org, linux-m68k , openrisc@lists.librecores.org, Greentime Hu , linux-mtd , Guan Xuetao , Linux ARM , Michal Simek , Parisc List , linux-mips@vger.kernel.org, alpha , "moderated list:NIOS2 ARCHITECTURE" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Nov 11, 2019 at 11:09:05AM +0100, Arnd Bergmann wrote: > Maybe we could move the definition into the atyfb driver itself? > > As I understand it, the difference between ioremap()/ioremap_nocache() > and ioremap_uc() only exists on pre-PAT x86-32 systems (i.e. 486, P5, > Ppro, PII, K6, VIA C3), while on more modern systems (all non-x86, > PentiumIII, Athlon, VIA C7) those three are meant to be synonyms > anyway. That's not how I understood it. Based on the code and the UC- explanation ioremap_uc always overrides the MTRR, which can still be present on more modern x86 systems. In fact I remember a patch floating around very recently adding another ioremap_uc caller in some Atom platform device driver that works around buggy MTRR tables. Also this series actually adds a new override and a few callers for ia64 platform code, which works very similar to x86 based on the comments in the code. That being said I'm not sure the callers in ia64 are really required, but it was the safest thing to do as part of this cleanup. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel