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=-5.5 required=3.0 tests=BAYES_00, 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 DA4F2C433E1 for ; Thu, 6 Aug 2020 16:52:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 27D342086A for ; Thu, 6 Aug 2020 16:52:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729649AbgHFQwh (ORCPT ); Thu, 6 Aug 2020 12:52:37 -0400 Received: from elvis.franken.de ([193.175.24.41]:36755 "EHLO elvis.franken.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729642AbgHFQwc (ORCPT ); Thu, 6 Aug 2020 12:52:32 -0400 Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1k3j81-0004MZ-00; Thu, 06 Aug 2020 18:52:29 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 70C2AC0C65; Thu, 6 Aug 2020 18:52:12 +0200 (CEST) Date: Thu, 6 Aug 2020 18:52:12 +0200 From: Thomas Bogendoerfer To: Jiaxun Yang Cc: Tiezhu Yang , Huacai Chen , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] MIPS: Introduce cmdline argument writecombine= Message-ID: <20200806165212.GA2754@alpha.franken.de> References: <1596697741-3561-1-git-send-email-yangtiezhu@loongson.cn> <10e04885-b775-e7db-b927-6400382fd32d@flygoat.com> <20200806101733.GA8136@alpha.franken.de> <9e563c75-ffaa-45b4-0e99-25a8b1eff828@flygoat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9e563c75-ffaa-45b4-0e99-25a8b1eff828@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 Thu, Aug 06, 2020 at 07:56:20PM +0800, Jiaxun Yang wrote: > Our current problem is Loongson's writecombine implementation seems buggy. > This is our platform issue rather than target hardware issue. ok, so simply clear cpu_data[0].writecombine for the fauly parts > And we don't even know which hardware is known to be good. The same graphic > card became a different story on different user's hand. find out what is broken and add the needed workarounds then. > I understood what Teizhu thought. For entry-level users, we don't want to > trouble > them, so we have writecombine disabled by default. However, for advanced > user > trying to tweak their system, we should leave a switch for them to get it > back. IMHO if we do it that way, we end up with millions of knobs for tweaking broken hardware, and nobody knows what's exactly broken. Sorry I won't go that way. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]