From patchwork Wed Dec 22 08:02:06 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wolfgang Denk X-Patchwork-Id: 76379 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from theia.denx.de (theia.denx.de [85.214.87.163]) by ozlabs.org (Postfix) with ESMTP id 0A636B7088 for ; Wed, 22 Dec 2010 19:02:17 +1100 (EST) Received: from localhost (localhost [127.0.0.1]) by theia.denx.de (Postfix) with ESMTP id 46C07280C4; Wed, 22 Dec 2010 09:02:15 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at theia.denx.de Received: from theia.denx.de ([127.0.0.1]) by localhost (theia.denx.de [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id eGL58IKlzmLo; Wed, 22 Dec 2010 09:02:15 +0100 (CET) Received: from theia.denx.de (localhost [127.0.0.1]) by theia.denx.de (Postfix) with ESMTP id 750FF280CD; Wed, 22 Dec 2010 09:02:13 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by theia.denx.de (Postfix) with ESMTP id 16336280CD for ; Wed, 22 Dec 2010 09:02:11 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at theia.denx.de Received: from theia.denx.de ([127.0.0.1]) by localhost (theia.denx.de [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id r2fU9n5A66kZ for ; Wed, 22 Dec 2010 09:02:09 +0100 (CET) X-policyd-weight: NOT_IN_SBL_XBL_SPAMHAUS=-1.5 NOT_IN_SPAMCOP=-1.5 NOT_IN_BL_NJABL=-1.5 (only DNSBL check requested) Received: from mail-out.m-online.net (mail-out.m-online.net [212.18.0.10]) by theia.denx.de (Postfix) with ESMTP id 05E19280C4 for ; Wed, 22 Dec 2010 09:02:07 +0100 (CET) Received: from frontend1.mail.m-online.net (frontend1.mail.intern.m-online.net [192.168.8.180]) by mail-out.m-online.net (Postfix) with ESMTP id B52811844260; Wed, 22 Dec 2010 09:02:06 +0100 (CET) X-Auth-Info: P3v5/JRCS0oGbRfylxQYXlzR3B+Qo1wJv6uSKQQdRts= Received: from diddl.denx.de (ppp-188-174-79-57.dynamic.mnet-online.de [188.174.79.57]) by smtp-auth.mnet-online.de (Postfix) with ESMTPA id E9E951C00163; Wed, 22 Dec 2010 09:02:06 +0100 (CET) Received: from gemini.denx.de (unknown [10.0.0.2]) by diddl.denx.de (Postfix) with ESMTP id BE8DC316E51C; Wed, 22 Dec 2010 09:02:06 +0100 (CET) Received: from gemini.denx.de (localhost.localdomain [127.0.0.1]) by gemini.denx.de (Postfix) with ESMTP id A0CA3EA652A; Wed, 22 Dec 2010 09:02:06 +0100 (CET) To: Alexander Holler From: Wolfgang Denk MIME-Version: 1.0 In-reply-to: <1292711230-3234-1-git-send-email-holler@ahsoftware.de> References: <1292711230-3234-1-git-send-email-holler@ahsoftware.de> Comments: In-reply-to Alexander Holler message dated "Sat, 18 Dec 2010 23:27:10 +0100." Date: Wed, 22 Dec 2010 09:02:06 +0100 Message-Id: <20101222080206.A0CA3EA652A@gemini.denx.de> Cc: u-boot@lists.denx.de Subject: Re: [U-Boot] [RFC PATCH v2] ARM: Avoid compiler optimization for usages of readb, writeb and friends. X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.9 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: u-boot-bounces@lists.denx.de Errors-To: u-boot-bounces@lists.denx.de Dear Alexander Holler, In message <1292711230-3234-1-git-send-email-holler@ahsoftware.de> you wrote: > gcc 4.5.1 seems to ignore (at least some) volatile definitions, > avoid that as done in the kernel. ... > +#define writeb(v,c) ({ __iowmb(); __arch_putb(v,c); }) > +#define writew(v,c) ({ __iowmb(); __arch_putw(v,c); }) > +#define writel(v,c) ({ __iowmb(); __arch_putl(v,c); }) http://www.codesourcery.com/archives/arm-gnu/msg03990.html explains why this construct is causing errors in cases where an additional read from the address is unsupported. Can you please try the following patch instead? ------------------------------------------------------------------------- From 4672bbddaf8ce7e17a99ba737782cc527d46e5eb Mon Sep 17 00:00:00 2001 From: Alexander Holler Date: Sat, 18 Dec 2010 23:27:10 +0100 Subject: [PATCH] ARM: Avoid compiler optimization for readb, writeb and friends. gcc 4.5.1 seems to ignore (at least some) volatile definitions, avoid that as done in the kernel. Reading C99 6.7.3 8 and the comment 114) there, I think it is a bug of that gcc version to ignore the volatile type qualifier used e.g. in __arch_getl(). Anyway, using a definition as in the kernel headers avoids such optimizations when gcc 4.5.1 is used. Maybe the headers as used in the current linux-kernel should be used, but to avoid large changes, I've just added a small change to the current headers. Signed-off-by: Alexander Holler Signed-off-by: Wolfgang Denk --- arch/arm/include/asm/io.h | 32 ++++++++++++++++++++------------ 1 files changed, 20 insertions(+), 12 deletions(-) diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h index ff1518e..647503a 100644 --- a/arch/arm/include/asm/io.h +++ b/arch/arm/include/asm/io.h @@ -117,21 +117,29 @@ extern inline void __raw_readsl(unsigned int addr, void *data, int longlen) *buf++ = __arch_getl(addr); } -#define __raw_writeb(v,a) __arch_putb(v,a) -#define __raw_writew(v,a) __arch_putw(v,a) -#define __raw_writel(v,a) __arch_putl(v,a) +#define __raw_writeb(v,a) __arch_putb(v,a) +#define __raw_writew(v,a) __arch_putw(v,a) +#define __raw_writel(v,a) __arch_putl(v,a) -#define __raw_readb(a) __arch_getb(a) -#define __raw_readw(a) __arch_getw(a) -#define __raw_readl(a) __arch_getl(a) +#define __raw_readb(a) __arch_getb(a) +#define __raw_readw(a) __arch_getw(a) +#define __raw_readl(a) __arch_getl(a) -#define writeb(v,a) __arch_putb(v,a) -#define writew(v,a) __arch_putw(v,a) -#define writel(v,a) __arch_putl(v,a) +/* + * TODO: The kernel offers some more advanced versions of barriers, it might + * have some advantages to use them instead of the simple one here. + */ +#define dmb() __asm__ __volatile__ ("" : : : "memory") +#define __iormb() dmb() +#define __iowmb() dmb() + +#define writeb(v,c) do { __iowmb(); __arch_putb(v,c); } while (0) +#define writew(v,c) do { __iowmb(); __arch_putw(v,c); } while (0) +#define writel(v,c) do { __iowmb(); __arch_putl(v,c); } while (0) -#define readb(a) __arch_getb(a) -#define readw(a) __arch_getw(a) -#define readl(a) __arch_getl(a) +#define readb(c) ({ u8 __v = __arch_getb(c); __iormb(); __v; }) +#define readw(c) ({ u16 __v = __arch_getw(c); __iormb(); __v; }) +#define readl(c) ({ u32 __v = __arch_getl(c); __iormb(); __v; }) /* * The compiler seems to be incapable of optimising constants