Re: [PATCH V2] scsi: mpt3sas: remove redundant wmb

[Sreekanth Reddy]

On Thu, Apr 20, 2017 at 7:58 AM, Martin K. Petersen
<martin.petersen@xxxxxxxxxx> wrote:
> Sinan Kaya <okaya@xxxxxxxxxxxxxx> 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 results in unnecessary performance loss and code duplication.
>>
>> writel already guarantees ordering for both cpu and bus. we don't need
>> additional wmb()
>
> Broadcom folks, please review!
>
> --
> Martin K. Petersen      Oracle Linux Engineering