Re: [PATCH v2 2/3] ARM: Use include/asm-generic/io.h

From: Catalin Marinas
Date: Sat Jul 12 2014 - 10:18:23 EST

On 12 Jul 2014, at 13:27, Arnd Bergmann <arnd@xxxxxxxx> wrote:

> 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.

I think this would be the easiest. But the asm-generic/io.h needs some
#ifndef iowrite16be checks.

(in arm64 we missed the iowrite*be barriers completely, so not broken by
this patch; Thierry could update arm64 as well with patch 3/3)

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