Subject: Re: [PATCH net] net/mlx4_en: correct the endianness of doorbell_qpn on big endian platform

From: Wei Yang <[email-masked]>
Date: Mon, 8 Dec 2014 22:42:37 +0800

On Mon, Dec 08, 2014 at 10:00:19AM +0000, David Laight wrote:
>From: Eric Dumazet
>> On Fri, 2014-12-05 at 21:31 -0800, David Miller wrote:
>> 
>> > Guys, let's figure out what we are doing with this patch.
>> > --
>> 
>> Oh well, patch is fine, please apply it, thanks !
>
>I'm not to sure that the patch doesn't generate a software byteswap
>followed by a byteswapping write on ppc - clearly not ideal.
>It might even generate back to back software byteswaps.
>
>If the write to the doorbell register includes a byteswap on BE (ppc)
>then there is no real value in keeping the value as BE.
>
>OTOH ppc ought to have ways of doing IO writes without the byteswap
>(and byteswapping accesses to non-io memory for that matter).
>
>What happens on a BE system with BE peripherals is another matter.

David

Thanks for your comment.

How about use __raw_writel() to replace the iowrite32()? Looks this is better,
if so, I will make up another version for this.

>	David

-- 
Richard Yang
Help you, Help me