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Subject: Re: [PATCH V2] scsi: mpt3sas: remove redundant wmb
To: Sreekanth Reddy <sreekanth.reddy@broadcom.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>
References: <1491591978-17880-1-git-send-email-okaya@codeaurora.org>
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Cc: Sinan Kaya <okaya@codeaurora.org>,
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        <suganath-prabu.subramani@broadcom.com>,
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From: Brian King <brking@linux.vnet.ibm.com>
Date: Fri, 21 Apr 2017 10:10:57 -0500
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On 04/21/2017 02:56 AM, Sreekanth Reddy wrote:
> On Thu, Apr 20, 2017 at 7:58 AM, Martin K. Petersen
> <martin.petersen@oracle.com> wrote:
>> Sinan Kaya <okaya@codeaurora.org> writes:
>>
>>> Due to relaxed ordering requirements on multiple architectures,
>>> drivers are required to use wmb/rmb/mb combinations when they need to
>>> guarantee observability between the memory and the HW.
>>>
>>> The mpt3sas driver is already using wmb() for this purpose.  However,
>>> it issues a writel following wmb(). writel() function on arm/arm64
>>> arhictectures have an embedded wmb() call inside.
> 
> [Sreekanth] Whether same thing applicable for SPARC & POWER
> architectures. If yes then we are fine with this patch changes.

This is also true for Power. 

Reviewed-by: Brian King <brking@linux.vnet.ibm.com>

-Brian

-- 
Brian King
Power Linux I/O
IBM Linux Technology Center