linux-kernel - RE: [PATCH] net: fec: only clear interrupt of handling queue in fec_enet_rx

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Message-ID: <DB8PR04MB67955258FC58D75DF9E1F72CE66D9@DB8PR04MB6795.eurprd04.prod.outlook.com>
Date:   Mon, 6 Dec 2021 13:15:12 +0000
From:   Joakim Zhang <qiangqing.zhang@....com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        Nicolas Diaz <nicolas.diaz@....com>,
        "rmk+kernel@....linux.org.uk" <rmk+kernel@....linux.org.uk>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH] net: fec: only clear interrupt of handling queue in
 fec_enet_rx_queue()


Hi Andrew,

> -----Original Message-----
> From: Andrew Lunn <andrew@...n.ch>
> Sent: 2021年12月6日 21:05
> To: Joakim Zhang <qiangqing.zhang@....com>
> Cc: davem@...emloft.net; kuba@...nel.org; Nicolas Diaz
> <nicolas.diaz@....com>; rmk+kernel@....linux.org.uk;
> netdev@...r.kernel.org; linux-kernel@...r.kernel.org; dl-linux-imx
> <linux-imx@....com>
> Subject: Re: [PATCH] net: fec: only clear interrupt of handling queue in
> fec_enet_rx_queue()
> 
> On Mon, Dec 06, 2021 at 05:05:53PM +0800, Joakim Zhang wrote:
> > Only clear interrupt of handling queue in fec_enet_rx_queue(), to
> > avoid missing packets caused by clear interrupt of other queues.
> >
> > Signed-off-by: Joakim Zhang <qiangqing.zhang@....com>
> > ---
> >  drivers/net/ethernet/freescale/fec_main.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/freescale/fec_main.c
> > b/drivers/net/ethernet/freescale/fec_main.c
> > index 09df434b2f87..eeefed3043ad 100644
> > --- a/drivers/net/ethernet/freescale/fec_main.c
> > +++ b/drivers/net/ethernet/freescale/fec_main.c
> > @@ -1506,7 +1506,12 @@ fec_enet_rx_queue(struct net_device *ndev,
> int budget, u16 queue_id)
> >  			break;
> >  		pkt_received++;
> >
> > -		writel(FEC_ENET_RXF, fep->hwp + FEC_IEVENT);
> > +		if (queue_id == 0)
> > +			writel(FEC_ENET_RXF_0, fep->hwp + FEC_IEVENT);
> > +		else if (queue_id == 1)
> > +			writel(FEC_ENET_RXF_1, fep->hwp + FEC_IEVENT);
> > +		else
> > +			writel(FEC_ENET_RXF_2, fep->hwp + FEC_IEVENT);
> 
> The change itself seems find.
> 
> Reviewed-by: Andrew Lunn <andrew@...n.ch>
> 
> But could it be moved out of the loop? If you have a budget of 64, don't you
> clear this bit 64 times? Can you just clearing it once on exit?

Apologize first, I have a formal patch but send out the informal one, I will re-send later, sorry for inconvenience.

About you question, yes, we need to clear this bit each time, the blamed patch introduced to avoiding interrupt flooding.

>     Andrew