[PATCH v4 5/6] IB/nes: Eliminate duplicate barriers on weakly-ordered archs

Code includes barrier() 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.

Create a new wrapper function with relaxed write operator. Use the new
wrapper when a write is following a barrier().

Signed-off-by: Sinan Kaya <redacted>
 drivers/infiniband/hw/nes/nes.h       |  5 +++++
 drivers/infiniband/hw/nes/nes_hw.c    | 21 ++++++++++++++-------
 drivers/infiniband/hw/nes/nes_mgt.c   | 15 ++++++++++-----
 drivers/infiniband/hw/nes/nes_nic.c   |  2 +-
 drivers/infiniband/hw/nes/nes_utils.c |  3 ++-
 drivers/infiniband/hw/nes/nes_verbs.c |  5 +++--
 6 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/drivers/infiniband/hw/nes/nes.h b/drivers/infiniband/hw/nes/nes.h
index 00c27291..85e007d 100644
+++ b/drivers/infiniband/hw/nes/nes.h

@@ -387,6 +387,11 @@ static inline void nes_write_indexed(struct nes_device *nesdev, u32 reg_index, u
 	spin_unlock_irqrestore(&nesdev->indexed_regs_lock, flags);
 }
 
+static inline void nes_write32_relaxed(void __iomem *addr, u32 val)
+{
+	writel_relaxed(val, addr);
+}

 static inline void nes_write32(void __iomem *addr, u32 val)
 {
 	writel(val, addr);

diff --git a/drivers/infiniband/hw/nes/nes_hw.c b/drivers/infiniband/hw/nes/nes_hw.c
index 18a7de1..568e17d 100644
+++ b/drivers/infiniband/hw/nes/nes_hw.c

@@ -1257,7 +1257,8 @@ int nes_destroy_cqp(struct nes_device *nesdev)
 
 	barrier();
 	/* Ring doorbell (5 WQEs) */
-	nes_write32(nesdev->regs+NES_WQE_ALLOC, 0x05800000 | nesdev->cqp.qp_id);
+	nes_write32_relaxed(nesdev->regs+NES_WQE_ALLOC,
+			    0x05800000 | nesdev->cqp.qp_id);