From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH v2 2/3] ARM: Use include/asm-generic/io.h Date: Sat, 12 Jul 2014 14:27:22 +0200 Message-ID: <201407121427.22668.arnd@arndb.de> References: <1405092672-18549-1-git-send-email-thierry.reding@gmail.com> <1405092672-18549-2-git-send-email-thierry.reding@gmail.com> <20140711162422.GF16321@arm.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from mout.kundenserver.de ([212.227.126.131]:58984 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752420AbaGLM1g (ORCPT ); Sat, 12 Jul 2014 08:27:36 -0400 In-Reply-To: <20140711162422.GF16321@arm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Catalin Marinas Cc: Thierry Reding , Russell King , Will Deacon , "linux-arm-kernel@lists.infradead.org" , "linux-arch@vger.kernel.org" , "linux-kernel@vger.kernel.org" On Friday 11 July 2014, Catalin Marinas wrote: > > On Fri, Jul 11, 2014 at 04:31:11PM +0100, Thierry Reding wrote: > > diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h > > index a78562f21aab..ef54f5c8a7ae 100644 > > --- a/arch/arm/include/asm/io.h > > +++ b/arch/arm/include/asm/io.h > [...] > > -#define iowrite16be(v,p) ({ __iowmb(); __raw_writew((__force __u16)cpu_to_be16(v), p); }) > > -#define iowrite32be(v,p) ({ __iowmb(); __raw_writel((__force __u32)cpu_to_be32(v), p); }) > > Aren't you losing the barrier semantics here? The generic iowrite*be() > functions call __raw_write*() directly which don't have a barrier > (write* accessors do). > Indeed, sorry for missing this. The generic implementation still makes sense for include/asm-generic, but arm32 and arm64 must provide their own versions here. An alternative would be to define #define iowrite32be(v, p) iowrite32(swab32(v), p) which is correct but can end up swapping multiple twice. Arnd