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=-2.2 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 CB1E8C38A2A for ; Fri, 8 May 2020 16:52:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ADA9321841 for ; Fri, 8 May 2020 16:52:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727099AbgEHQwx (ORCPT ); Fri, 8 May 2020 12:52:53 -0400 Received: from elvis.franken.de ([193.175.24.41]:45060 "EHLO elvis.franken.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727097AbgEHQwx (ORCPT ); Fri, 8 May 2020 12:52:53 -0400 Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1jX6Ey-00060q-00; Fri, 08 May 2020 18:52:48 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id F1396C043D; Fri, 8 May 2020 18:52:35 +0200 (CEST) Date: Fri, 8 May 2020 18:52:35 +0200 From: Thomas Bogendoerfer To: Jiaxun Yang Cc: linux-mips@vger.kernel.org, chenhc@lemote.com, john.garry@huawei.com Subject: Re: [PATCH RESEND v3 2/3] MIPS: Introduce PCI_IO_VMMAP Message-ID: <20200508165235.GA24425@alpha.franken.de> References: <20200426114806.1176629-1-jiaxun.yang@flygoat.com> <20200508114438.3092215-1-jiaxun.yang@flygoat.com> <20200508114438.3092215-2-jiaxun.yang@flygoat.com> <20200508161102.GA23094@alpha.franken.de> <18B84249-7CA1-411E-B595-6E215D8C9C34@flygoat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <18B84249-7CA1-411E-B595-6E215D8C9C34@flygoat.com> 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 Sat, May 09, 2020 at 12:22:25AM +0800, Jiaxun Yang wrote: > > > 于 2020年5月9日 GMT+08:00 上午12:11:02, Thomas Bogendoerfer 写到: > >On Fri, May 08, 2020 at 07:44:37PM +0800, Jiaxun Yang wrote: > >> Define PCI_IOBASE for MIPS at the strat of kernel mapping segment. > >> That would allow virt address of I/O ports to be dynamicly mapped. > >> So we'll be able to combine multiple MMIO ranges into I/O ports > >> and thus we can take advantage of logic_pio mechanism. > > > >What is the advantage ? > > > >From my point of view this will be slower because of TLB faults for > >PCI IO space accesses. > > Advantage is we can use logic_pio to manage multiple I/O Port ranges. and what exactly does this buy us ? I looked at lib/logic_pio.c and there didn't appear anything in my mind other than yet another interface for doing the same thing... > That can help us reuse generic PCI I/O design. please explain this. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]