From: Andy Shevchenko <andy.shevchenko@gmail.com>
Subject: Re: [PATCH v5 3/6] iomap: introduce io{read|write}64_{lo_hi|hi_lo}
Date: Mon, 31 Jul 2017 20:58:25 +0300
Message-ID: <CAHp75VdE-xRHDEfmmURtoak6+4Vga4szLnDkGjtJHm47DZRCAQ@mail.gmail.com>
References: <20170726231917.6073-1-logang@deltatee.com> <20170726231917.6073-4-logang@deltatee.com>
 <CAHp75Vcv7UCpnGY+mL7CMU5u9hCUxwaYWNsg58BoWBJGAFX4tQ@mail.gmail.com>
 <5c52d908-3b77-c5c6-99a7-1164d878ac95@deltatee.com> <CAHp75Ve619EE9ePy2zj+MjS7-MW3u_k2BQ5kc9iFBMYYQ9nMWQ@mail.gmail.com>
 <3a4c9453-20be-8164-85eb-5ad4d596a299@deltatee.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Linux-Arch <linux-arch@vger.kernel.org>,
        linux-ntb@googlegroups.com,
        linux-crypto <linux-crypto@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        =?UTF-8?Q?Horia_Geant=C4=83?= <horia.geanta@nxp.com>,
        Stephen Bates <sbates@raithlin.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Suresh Warrier <warrier@linux.vnet.ibm.com>,
        Nicholas Piggin <npiggin@gmail.com>
To: Logan Gunthorpe <logang@deltatee.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <3a4c9453-20be-8164-85eb-5ad4d596a299@deltatee.com>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: linux-crypto.vger.kernel.org

On Mon, Jul 31, 2017 at 7:31 PM, Logan Gunthorpe <logang@deltatee.com> wrote:
> On 31/07/17 10:10 AM, Andy Shevchenko wrote:
>> Some drivers (hardware) would like to have non-atomic MMIO accesses
>> when readq() defined
>
> Huh? But that's the whole point of the io64-nonatomic header. If a
> driver wants a specific non-atomic access they should just code two 32
> bit accesses.

You mean to call them directly as lo_hi_XXX() or hi_lo_XXX() ?
Yes it would work.

>> In case of readq() / writeq() it's defined by the order of inclusion:
>>
>> 1)
>> include <...non-atomic...>
>> include <linux/io.h>
>>
>> Always non-atomic will be used.
>
> I'm afraid you're wrong about this. The io-64-nonatomic-xx header
> includes linux/io.h. Thus the order of the includes doesn't matter and
> it will always auto switch. In any case, making an interface do
> different things depending on the order of include files is *completely*
> insane.

Yes, you are right. I was thinking about something unrelated.

-- 
With Best Regards,
Andy Shevchenko