From: Arnd Bergmann <arnd@arndb.de>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Thierry Reding <thierry.reding@gmail.com>,
Russell King <linux@arm.linux.org.uk>,
Will Deacon <Will.Deacon@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 2/3] ARM: Use include/asm-generic/io.h
Date: Sat, 12 Jul 2014 14:27:22 +0200 [thread overview]
Message-ID: <201407121427.22668.arnd@arndb.de> (raw)
In-Reply-To: <20140711162422.GF16321@arm.com>
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
next prev parent reply other threads:[~2014-07-12 12:27 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-11 15:31 [PATCH v2 1/3] asm-generic/io.h: Implement generic {read,write}s*() Thierry Reding
2014-07-11 15:31 ` [PATCH v2 2/3] ARM: Use include/asm-generic/io.h Thierry Reding
2014-07-11 15:31 ` Thierry Reding
2014-07-11 16:24 ` Catalin Marinas
2014-07-12 12:27 ` Arnd Bergmann [this message]
2014-07-12 14:18 ` Catalin Marinas
2014-07-11 15:31 ` [PATCH v2 3/3] arm64: " Thierry Reding
2014-07-11 15:31 ` Thierry Reding
2014-07-11 16:18 ` [PATCH v2 1/3] asm-generic/io.h: Implement generic {read,write}s*() Catalin Marinas
2014-07-11 21:59 ` Stephen Boyd
2014-07-14 9:10 ` Thierry Reding
2014-07-14 17:23 ` Stephen Boyd
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