From mboxrd@z Thu Jan 1 00:00:00 1970 From: okaya@codeaurora.org (Sinan Kaya) Date: Mon, 19 Mar 2018 22:47:43 -0400 Subject: [PATCH v4 1/6] RDMA/bnxt_re: Eliminate duplicate barriers on weakly-ordered archs In-Reply-To: <1521514068-8856-1-git-send-email-okaya@codeaurora.org> References: <1521514068-8856-1-git-send-email-okaya@codeaurora.org> Message-ID: <1521514068-8856-2-git-send-email-okaya@codeaurora.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Code includes wmb() followed by writel(). writel() already has a barrier on some architectures like arm64. This ends up CPU observing two barriers back to back before executing the register write. Since code already has an explicit barrier call, changing writel() to writel_relaxed(). Signed-off-by: Sinan Kaya --- drivers/infiniband/hw/bnxt_re/qplib_rcfw.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c index 8329ec6..4a6b981 100644 --- a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c +++ b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c @@ -181,10 +181,10 @@ static int __send_message(struct bnxt_qplib_rcfw *rcfw, struct cmdq_base *req, /* ring CMDQ DB */ wmb(); - writel(cmdq_prod, rcfw->cmdq_bar_reg_iomem + - rcfw->cmdq_bar_reg_prod_off); - writel(RCFW_CMDQ_TRIG_VAL, rcfw->cmdq_bar_reg_iomem + - rcfw->cmdq_bar_reg_trig_off); + writel_relaxed(cmdq_prod, rcfw->cmdq_bar_reg_iomem + + rcfw->cmdq_bar_reg_prod_off); + writel_relaxed(RCFW_CMDQ_TRIG_VAL, rcfw->cmdq_bar_reg_iomem + + rcfw->cmdq_bar_reg_trig_off); done: spin_unlock_irqrestore(&cmdq->lock, flags); /* Return the CREQ response pointer */ -- 2.7.4