netdev - Re: [PATCH net] net/mlx4_en: correct the endianness of doorbell

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Date:	Mon, 15 Dec 2014 09:32:49 +0800
From:	Wei Yang <weiyang@...ux.vnet.ibm.com>
To:	David Miller <davem@...emloft.net>
Cc:	weiyang@...ux.vnet.ibm.com, David.Laight@...LAB.COM,
	eric.dumazet@...il.com, netdev@...r.kernel.org,
	gideonn@...lanox.com, edumazet@...gle.com, amirv@...lanox.com
Subject: Re: [PATCH net] net/mlx4_en: correct the endianness of doorbell_qpn
 on big endian platform

On Sat, Dec 13, 2014 at 11:43:20PM -0500, David Miller wrote:
>From: Wei Yang <weiyang@...ux.vnet.ibm.com>
>Date: Sat, 13 Dec 2014 11:13:38 +0800
>
>> On Mon, Dec 08, 2014 at 10:42:37PM +0800, Wei Yang wrote:
>> If you prefer this way, I would like to send a new version for this.
>> Is it ok for you?
>
>I'm not so sure.  There are implications when using the __raw_*()
>routines.
>
>In particular, using __raw_{read,write}l() also means that the usual
>necessary I/O memory barriers are not being performed.
>
>There are therefore no ordering guarantees between __raw_*() and other
>I/O or memory accesses whatsoever.

Thanks David.

Actually, the last mail is asking David Laight. I am trying to understanding
his comment and Amir told me he was suggesting to use __raw_*() version.

Hmm... this is really a problem found in the v3.18-rc1 and the root cause is
the endianess. I am ok to use any method to fix this problem, even revert it.
Could the maintainer from Mellanox gives me a word?

-- 
Richard Yang
Help you, Help me

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