linux-kernel - Re: [PATCH v13 01/10] iomap: Use correct endian conversion function in mmio

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Message-ID: <6a063b65-668a-ef9c-696e-8c378e6b2640@deltatee.com>
Date:   Mon, 26 Mar 2018 14:33:13 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        linux-ntb@...glegroups.com,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Horia Geantă <horia.geanta@....com>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Luc Van Oostenryck <luc.vanoostenryck@...il.com>
Subject: Re: [PATCH v13 01/10] iomap: Use correct endian conversion function
 in mmio_writeXXbe



On 26/03/18 01:50 PM, Arnd Bergmann wrote:
> I wouldn't expect it to matter: the byte swap is almost always much
> cheaper compared to the actual bus access for the MMIO, and I
> would also guess that modern compilers can eliminate the double
> byte swap on architectures where writel() is an inline function. Most of
> the important architectures use ARCH_USE_BUILTIN_BSWAP, which
> guarantees that.

Fair enough. Sometime this week I'll update my patch set to change that.

Thanks,

Logan