linux-kernel - [PATCH] net: ethernet: ti: cpsw: fix rx-usecs interrupt pacing consistency

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Message-Id: <1464873292-17011-1-git-send-email-ivan.khoronzhuk@linaro.org>
Date:	Thu,  2 Jun 2016 16:14:52 +0300
From:	Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
To:	linux-kernel@...r.kernel.org, mugunthanvnm@...com
Cc:	grygorii.strashko@...com, linux-omap@...r.kernel.org,
	netdev@...r.kernel.org,
	Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
Subject: [PATCH] net: ethernet: ti: cpsw: fix rx-usecs interrupt pacing consistency

The rx-usecs shouldn't be changed while interface down/up.
Currently, for instance, if it's set to 100us, after interface
down/up it's 500us. It's a hidden bug that can lead to lavish
interrupt pacing time increasing while "down/up" up to max value.

Steps to reproduce:
- set rx-usecs to be 100us
- down/up interface
- read new unexpected rx-usecs

Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
---

Based on ti-linux-4.4.y

 drivers/net/ethernet/ti/cpsw.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
index 7b44587..9919cb3 100644
--- a/drivers/net/ethernet/ti/cpsw.c
+++ b/drivers/net/ethernet/ti/cpsw.c
@@ -1352,7 +1352,7 @@ static int cpsw_ndo_open(struct net_device *ndev)
 	if (priv->coal_intvl != 0) {
 		struct ethtool_coalesce coal;
 
-		coal.rx_coalesce_usecs = (priv->coal_intvl << 4);
+		coal.rx_coalesce_usecs = priv->coal_intvl;
 		cpsw_set_coalesce(ndev, &coal);
 	}
 
-- 
1.9.1