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.
Create a new wrapper function with relaxed write operator. Use the new
wrapper when a write is following a wmb().
Since code already has an explicit barrier call, changing writel() to
writel_relaxed().
Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx>
---
drivers/net/ethernet/broadcom/bnxt/bnxt.c | 2 +-
drivers/net/ethernet/broadcom/bnxt/bnxt.h | 11 ++++++++++-
drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c | 2 +-
3 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 1500243..befb538 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -1922,7 +1922,7 @@ static int bnxt_poll_work(struct bnxt *bp, struct bnxt_napi *bnapi, int budget)
/* Sync BD data before updating doorbell */
wmb();
- bnxt_db_write(bp, db, DB_KEY_TX | prod);
+ bnxt_db_write_relaxed(bp, db, DB_KEY_TX | prod);
}
cpr->cp_raw_cons = raw_cons;
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
index 1989c47..4c0d048 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -1402,11 +1402,20 @@ static inline u32 bnxt_tx_avail(struct bnxt *bp, struct bnxt_tx_ring_info *txr)
}
/* For TX and RX ring doorbells */
+static inline void bnxt_db_write_relaxed(struct bnxt *bp, void __iomem *db,
+ u32 val)
+{
+ writel_relaxed(val, db);
+ if (bp->flags & BNXT_FLAG_DOUBLE_DB)
+ writel_relaxed(val, db);
+}
+
+/* For TX and RX ring doorbells */
static inline void bnxt_db_write(struct bnxt *bp, void __iomem *db, u32 val)
{
writel(val, db);
if (bp->flags & BNXT_FLAG_DOUBLE_DB)
- writel(val, db);
+ writel_relaxed(val, db);
}
extern const u16 bnxt_lhint_arr[];
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
index 1801582..a1b1060 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
@@ -2403,7 +2403,7 @@ static int bnxt_run_loopback(struct bnxt *bp)
/* Sync BD data before updating doorbell */
wmb();
- bnxt_db_write(bp, txr->tx_doorbell, DB_KEY_TX | txr->tx_prod);
+ bnxt_db_write_relaxed(bp, txr->tx_doorbell, DB_KEY_TX | txr->tx_prod);
rc = bnxt_poll_loopback(bp, pkt_size);
dma_unmap_single(&bp->pdev->dev, map, pkt_size, PCI_DMA_TODEVICE);
--
2.7.4
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