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scsi: mpt3sas: remove redundant wmb 

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.

This results in unnecessary performance loss and code duplication.

writel already guarantees ordering for both cpu and bus. we don't need
additional wmb()

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Acked-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
hifive-unleashed-5.1
Sinan Kaya 2017-04-07 15:06:18 -04:00 committed by Martin K. Petersen
parent cfd2aff711
commit b1391a5bf8
1 changed files with 0 additions and 2 deletions
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2
drivers/scsi/mpt3sas/mpt3sas_base.c
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@ -1025,7 +1025,6 @@ _base_interrupt(int irq, void *bus_id)
0 : ioc->reply_free_host_index + 1;
ioc->reply_free[ioc->reply_free_host_index] =
cpu_to_le32(reply);
wmb();
writel(ioc->reply_free_host_index,
&ioc->chip->ReplyFreeHostIndex);
}
@ -1074,7 +1073,6 @@ _base_interrupt(int irq, void *bus_id)
return IRQ_NONE;
}
wmb();
if (ioc->is_warpdrive) {
writel(reply_q->reply_post_host_index,
ioc->reply_post_host_index[msix_index]);