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

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Date:   Wed, 21 Mar 2018 18:28:44 +0100
From:   Luc Van Oostenryck <luc.vanoostenryck@...il.com>
To:     Logan Gunthorpe <logang@...tatee.com>
Cc:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-ntb@...glegroups.com, linux-crypto@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        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>
Subject: Re: [PATCH v13 01/10] iomap: Use correct endian conversion function
 in mmio_writeXXbe

On Wed, Mar 21, 2018 at 10:37:36AM -0600, Logan Gunthorpe wrote:
> The semantics of the iowriteXXbe() functions are to write a
> value in CPU endianess to an IO register that is known by the
> caller to be in Big Endian. The mmio_writeXXbe() macro, which
> is called by iowriteXXbe(), should therefore use cpu_to_beXX()
> instead of beXX_to_cpu().
> 
> Seeing both beXX_to_cpu() and cpu_to_beXX() are both functionally
> implemented as either null operations or swabXX operations there
> was no noticable bug here. But it is confusing for both developers
> and code analysis tools alike.
> 
> Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
> Cc: Philippe Ombredanne <pombredanne@...b.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Kate Stewart <kstewart@...uxfoundation.org>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Luc Van Oostenryck <luc.vanoostenryck@...il.com>
> ---
>  lib/iomap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/iomap.c b/lib/iomap.c
> index 541d926da95e..be120c13d6cc 100644
> --- a/lib/iomap.c
> +++ b/lib/iomap.c
> @@ -106,8 +106,8 @@ EXPORT_SYMBOL(ioread32be);
>  #endif
>  
>  #ifndef mmio_write16be
> -#define mmio_write16be(val,port) __raw_writew(be16_to_cpu(val),port)
> -#define mmio_write32be(val,port) __raw_writel(be32_to_cpu(val),port)
> +#define mmio_write16be(val,port) __raw_writew(cpu_to_be16(val),port)
> +#define mmio_write32be(val,port) __raw_writel(cpu_to_be32(val),port)
>  #endif
>  
>  void iowrite8(u8 val, void __iomem *addr)
> -- 
> 2.11.0
> 

LGTM, feel free to add my
Reviewed-by: Luc Van Oostenryck <luc.vanoostenryck@...il.com>

-- Luc