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(). Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx> --- drivers/net/ethernet/chelsio/cxgb3/adapter.h | 7 +++++++ drivers/net/ethernet/chelsio/cxgb3/sge.c | 19 ++++++++++--------- 2 files changed, 17 insertions(+), 9 deletions(-) diff --git a/drivers/net/ethernet/chelsio/cxgb3/adapter.h b/drivers/net/ethernet/chelsio/cxgb3/adapter.h index 087ff0f..0e21e66 100644 --- a/drivers/net/ethernet/chelsio/cxgb3/adapter.h +++ b/drivers/net/ethernet/chelsio/cxgb3/adapter.h @@ -281,6 +281,13 @@ static inline void t3_write_reg(struct adapter *adapter, u32 reg_addr, u32 val) writel(val, adapter->regs + reg_addr); } +static inline void t3_write_reg_relaxed(struct adapter *adapter, u32 reg_addr, + u32 val) +{ + CH_DBG(adapter, MMIO, "setting register 0x%x to 0x%x\n", reg_addr, val); + writel_relaxed(val, adapter->regs + reg_addr); +} + static inline struct port_info *adap2pinfo(struct adapter *adap, int idx) { return netdev_priv(adap->port[idx]); diff --git a/drivers/net/ethernet/chelsio/cxgb3/sge.c b/drivers/net/ethernet/chelsio/cxgb3/sge.c index e988caa..0baab06 100644 --- a/drivers/net/ethernet/chelsio/cxgb3/sge.c +++ b/drivers/net/ethernet/chelsio/cxgb3/sge.c @@ -487,7 +487,8 @@ static inline void ring_fl_db(struct adapter *adap, struct sge_fl *q) if (q->pend_cred >= q->credits / 4) { q->pend_cred = 0; wmb(); - t3_write_reg(adap, A_SG_KDOORBELL, V_EGRCNTX(q->cntxt_id)); + t3_write_reg_relaxed(adap, A_SG_KDOORBELL, + V_EGRCNTX(q->cntxt_id)); } } @@ -1058,8 +1059,8 @@ static inline void check_ring_tx_db(struct adapter *adap, struct sge_txq *q) } #else wmb(); /* write descriptors before telling HW */ - t3_write_reg(adap, A_SG_KDOORBELL, - F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id)); + t3_write_reg_relaxed(adap, A_SG_KDOORBELL, + F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id)); #endif } @@ -1510,8 +1511,8 @@ static int ctrl_xmit(struct adapter *adap, struct sge_txq *q, } spin_unlock(&q->lock); wmb(); - t3_write_reg(adap, A_SG_KDOORBELL, - F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id)); + t3_write_reg_relaxed(adap, A_SG_KDOORBELL, + F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id)); return NET_XMIT_SUCCESS; } @@ -1554,8 +1555,8 @@ static void restart_ctrlq(unsigned long data) spin_unlock(&q->lock); wmb(); - t3_write_reg(qs->adap, A_SG_KDOORBELL, - F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id)); + t3_write_reg_relaxed(qs->adap, A_SG_KDOORBELL, + F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id)); } /* @@ -1793,8 +1794,8 @@ again: reclaim_completed_tx(adap, q, TX_RECLAIM_CHUNK); #endif wmb(); if (likely(written)) - t3_write_reg(adap, A_SG_KDOORBELL, - F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id)); + t3_write_reg_relaxed(adap, A_SG_KDOORBELL, + F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id)); } /** -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html