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From:   Jiangfeng Xiao <xiaojiangfeng@huawei.com>
To:     <davem@davemloft.net>, <yisen.zhuang@huawei.com>,
        <salil.mehta@huawei.com>, <xiaojiangfeng@huawei.com>
CC:     <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <leeyou.li@huawei.com>, <xiaowei774@huawei.com>,
        <nixiaoming@huawei.com>
Subject: [PATCH v1 2/3] net: hisilicon: fix hip04-xmit never return TX_BUSY
Date:   Sat, 3 Aug 2019 20:31:40 +0800
Message-ID: <1564835501-90257-3-git-send-email-xiaojiangfeng@huawei.com>
In-Reply-To: <1564835501-90257-1-git-send-email-xiaojiangfeng@huawei.com>
References: <1564835501-90257-1-git-send-email-xiaojiangfeng@huawei.com>
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TX_DESC_NUM is 256, in tx_count, the maximum value of
mod(TX_DESC_NUM - 1) is 254, the variable "count" in
the hip04_mac_start_xmit function is never equal to
(TX_DESC_NUM - 1), so hip04_mac_start_xmit never
return NETDEV_TX_BUSY.

tx_count is modified to mod(TX_DESC_NUM) so that
the maximum value of tx_count can reach
(TX_DESC_NUM - 1), then hip04_mac_start_xmit can reurn
NETDEV_TX_BUSY.

Signed-off-by: Jiangfeng Xiao <xiaojiangfeng@huawei.com>
---
 drivers/net/ethernet/hisilicon/hip04_eth.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/hisilicon/hip04_eth.c b/drivers/net/ethernet/hisilicon/hip04_eth.c
index 1e1b154..d775b98 100644
--- a/drivers/net/ethernet/hisilicon/hip04_eth.c
+++ b/drivers/net/ethernet/hisilicon/hip04_eth.c
@@ -248,7 +248,7 @@ struct hip04_priv {
 
 static inline unsigned int tx_count(unsigned int head, unsigned int tail)
 {
-	return (head - tail) % (TX_DESC_NUM - 1);
+	return (head - tail) % TX_DESC_NUM;
 }
 
 static void hip04_config_port(struct net_device *ndev, u32 speed, u32 duplex)
-- 
1.8.5.6