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.
The kernel has been updated to support relaxed read/write
API to be supported across all architectures now.
The right thing was to either call __raw_writel/__raw_readl or
write_relaxed/read_relaxed for multi-arch compatibility.
Signed-off-by: Sinan Kaya <ok...@codeaurora.org>
---
drivers/scsi/mpt3sas/mpt3sas_base.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c
b/drivers/scsi/mpt3sas/mpt3sas_base.c
index 5b7aec5..6e42036 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_base.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_base.c
@@ -1026,8 +1026,8 @@ static int mpt3sas_remove_dead_ioc_func(void *arg)
ioc->reply_free[ioc->reply_free_host_index] =
cpu_to_le32(reply);
wmb();
- writel(ioc->reply_free_host_index,
- &ioc->chip->ReplyFreeHostIndex);
+ writel_relaxed(ioc->reply_free_host_index,
+ &ioc->chip->ReplyFreeHostIndex);
}
}
@@ -1076,8 +1076,8 @@ static int mpt3sas_remove_dead_ioc_func(void *arg)
wmb();
if (ioc->is_warpdrive) {
- writel(reply_q->reply_post_host_index,
- ioc->reply_post_host_index[msix_index]);
+ writel_relaxed(reply_q->reply_post_host_index,
+ ioc->reply_post_host_index[msix_index]);
atomic_dec(&reply_q->busy);
return IRQ_HANDLED;
}
@@ -1098,13 +1098,14 @@ static int mpt3sas_remove_dead_ioc_func(void *arg)
* value in MSIxIndex field.
*/
if (ioc->combined_reply_queue)
- writel(reply_q->reply_post_host_index | ((msix_index & 7) <<
- MPI2_RPHI_MSIX_INDEX_SHIFT),
- ioc->replyPostRegisterIndex[msix_index/8]);
+ writel_relaxed(reply_q->reply_post_host_index |
+ ((msix_index & 7) <<
+ MPI2_RPHI_MSIX_INDEX_SHIFT),
+ ioc->replyPostRegisterIndex[msix_index/8]);
else
- writel(reply_q->reply_post_host_index | (msix_index <<
- MPI2_RPHI_MSIX_INDEX_SHIFT),
- &ioc->chip->ReplyPostHostIndex);
+ writel_relaxed(reply_q->reply_post_host_index |
+ (msix_index << MPI2_RPHI_MSIX_INDEX_SHIFT),
+ &ioc->chip->ReplyPostHostIndex);
atomic_dec(&reply_q->busy);
return IRQ_HANDLED;
}
--
1.9.1
