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=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 744D9C2D0DB for ; Fri, 24 Jan 2020 14:24:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 552702072C for ; Fri, 24 Jan 2020 14:24:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387684AbgAXOYm (ORCPT ); Fri, 24 Jan 2020 09:24:42 -0500 Received: from elvis.franken.de ([193.175.24.41]:59877 "EHLO elvis.franken.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389799AbgAXOYm (ORCPT ); Fri, 24 Jan 2020 09:24:42 -0500 X-Greylist: delayed 980 seconds by postgrey-1.27 at vger.kernel.org; Fri, 24 Jan 2020 09:24:41 EST Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1iuzdC-0003XT-00; Fri, 24 Jan 2020 15:08:18 +0100 Received: by alpha.franken.de (Postfix, from userid 1000) id 454FCC0784; Fri, 24 Jan 2020 15:07:51 +0100 (CET) Date: Fri, 24 Jan 2020 15:07:51 +0100 From: Thomas Bogendoerfer To: Paul Burton Cc: Jiaxun Yang , linux-mips@vger.kernel.org, chenhc@lemote.com, paul.burton@mips.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] MIPS: Introduce aligned IO memory operations Message-ID: <20200124140751.GA17030@alpha.franken.de> References: <20200114122343.163685-1-jiaxun.yang@flygoat.com> <20200122184506.7zbzetn5xturxamj@pburton-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200122184506.7zbzetn5xturxamj@pburton-laptop> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Wed, Jan 22, 2020 at 10:45:06AM -0800, Paul Burton wrote: > Hi Jiaxun, > > On Tue, Jan 14, 2020 at 08:23:43PM +0800, Jiaxun Yang wrote: > > Some platforms, such as Loongson64 or QEMU/KVM, don't support unaligned > > instructions like lwl or lwr in IO memory access. However, our current > > IO memcpy/memset is wired to the generic implementation, which leads > > to a fatal result. > > Hmm, I wonder if we should just do this unconditionally on all systems. > I can't think of a reason it'd ever be a good idea to use lwl/lwr on an > MMIO device. Any thoughts on that? depends on the type of device. I can see benefits for framebuffers and memory devices since memset/memcpy are more optimised than the function in this patch. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]