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

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Date:	Thu, 2 Jun 2016 16:30:00 +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
Subject: Re: [PATCH] net: ethernet: ti: cpsw: fix rx-usecs interrupt pacing
 consistency

On 02.06.16 16:14, Ivan Khoronzhuk wrote:
> 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
Please ignore this line, it's added by mistake.
The patch is based on master.


>
>   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);
>   	}
>
>

-- 
Regards,
Ivan Khoronzhuk