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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 1B4FCC0650F for ; Wed, 14 Aug 2019 05:39:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E5F4620843 for ; Wed, 14 Aug 2019 05:39:01 +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="PakH2jaX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727469AbfHNFiy (ORCPT ); Wed, 14 Aug 2019 01:38:54 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:59902 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727095AbfHNFix (ORCPT ); Wed, 14 Aug 2019 01:38:53 -0400 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=SlVqJKDhHhOV65ho42xhKFAezVWVkPicox2Ec3tGxgk=; b=PakH2jaXbBToCfuos4t+CAubT lwx/wRgTpVs9alNcOCtl8VsIzzS5fl6E+TxQWxiS+iNy2NehAm1OUonV55GXj4rxxGY3Q3YpZcw48 qiEr3JyqLHobUgzDpC0ed+RLOkOUf/Njyg8q7o1fixpxsAAK/kDkij4TVOL7Mh9F4JEOHws06O99F nSNgA1gaW0bE04qxe7mj+XreHnHfGTqBJgH1LtISXjFlGVsENnC9n/8IR5YO1g3DbuE0O2Z0W7xlu 5BekPF04RbiJY2dlIvnotC7vUgpmOuhtWaLRixG/ov1LsbQpe4ec4Fj08zrXQN9ygD/jKrd6MBo5h MitR12Z7Q==; Received: from hch by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1hxlzf-0007CA-DV; Wed, 14 Aug 2019 05:38:43 +0000 Date: Tue, 13 Aug 2019 22:38:43 -0700 From: Christoph Hellwig To: Christophe Leroy Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , npiggin@gmail.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 02/10] powerpc/mm: rework io-workaround invocation. Message-ID: <20190814053843.GB27497@infradead.org> References: <6bc35eca507359075528bc0e55938bc1ce8ee485.1565726867.git.christophe.leroy@c-s.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.4 (2019-03-13) 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 On Tue, Aug 13, 2019 at 08:11:34PM +0000, Christophe Leroy wrote: > ppc_md.ioremap() is only used for I/O workaround on CELL platform, > so indirect function call can be avoided. > > This patch reworks the io-workaround and ioremap() functions to > use static keys for the activation of io-workaround. > > When CONFIG_PPC_IO_WORKAROUNDS or CONFIG_PPC_INDIRECT_MMIO are not > selected, the I/O workaround ioremap() voids and the static key is > not used at all. Why bother with the complex static key? ioremap isn't exactly a fast path. Just make it a normal branch if enabled, with the option to compile it out entirely as in your patch.