netdev - Re: [PATCH net-next V2 06/16] net: fec: don't clear all rx queue bits when just one is being checked

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Message-ID: <56D9B54B.8020309@boundarydevices.com>
Date:	Fri, 4 Mar 2016 09:18:19 -0700
From:	Troy Kisky <troy.kisky@...ndarydevices.com>
To:	Fugang Duan <fugang.duan@....com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"b38611@...escale.com" <b38611@...escale.com>,
	"linux@....linux.org.uk" <linux@....linux.org.uk>
Cc:	"fabio.estevam@...escale.com" <fabio.estevam@...escale.com>,
	"l.stach@...gutronix.de" <l.stach@...gutronix.de>,
	"andrew@...n.ch" <andrew@...n.ch>,
	"tremyfr@...il.com" <tremyfr@...il.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"laci@...ndarydevices.com" <laci@...ndarydevices.com>,
	"shawnguo@...nel.org" <shawnguo@...nel.org>,
	"johannes@...solutions.net" <johannes@...solutions.net>,
	"stillcompiling@...il.com" <stillcompiling@...il.com>,
	"sergei.shtylyov@...entembedded.com" 
	<sergei.shtylyov@...entembedded.com>,
	"arnd@...db.de" <arnd@...db.de>
Subject: Re: [PATCH net-next V2 06/16] net: fec: don't clear all rx queue bits
 when just one is being checked

On 3/4/2016 2:11 AM, Fugang Duan wrote:
> From: Troy Kisky <troy.kisky@...ndarydevices.com>Sent: Thursday, February 25, 2016 8:37 AM
>> To: netdev@...r.kernel.org; davem@...emloft.net; b38611@...escale.com
>> Cc: fabio.estevam@...escale.com; l.stach@...gutronix.de; andrew@...n.ch;
>> tremyfr@...il.com; linux@....linux.org.uk; linux-arm-
>> kernel@...ts.infradead.org; laci@...ndarydevices.com; shawnguo@...nel.org;
>> johannes@...solutions.net; stillcompiling@...il.com;
>> sergei.shtylyov@...entembedded.com; arnd@...db.de; Troy Kisky
>> <troy.kisky@...ndarydevices.com>
>> Subject: [PATCH net-next V2 06/16] net: fec: don't clear all rx queue bits when
>> just one is being checked
>>
>> FEC_ENET_RXF is 3 separate bits, we only check one queue at a time. So, when
>> the last queue is being checked, it is bad to remove the interrupt on the 1st
>> queue.
>>
>> Also, since this is now done in the napi routine and not the interrupt, it is not
>> needed.
>>
>> Signed-off-by: Troy Kisky <troy.kisky@...ndarydevices.com>
>> ---
>>  drivers/net/ethernet/freescale/fec_main.c | 2 --
>>  1 file changed, 2 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/freescale/fec_main.c
>> b/drivers/net/ethernet/freescale/fec_main.c
>> index 610cf6c..791f385 100644
>> --- a/drivers/net/ethernet/freescale/fec_main.c
>> +++ b/drivers/net/ethernet/freescale/fec_main.c
>> @@ -1338,8 +1338,6 @@ static int fec_rxq(struct net_device *ndev, struct
>> fec_enet_private *fep,
>>  			break;
>>  		pkt_received++;
>>
>> -		writel(FEC_ENET_RXF, fep->hwp + FEC_IEVENT);
>> -
> 
> We should clear the related rx queue ievent, not remove the code.
> Pls see commit: db3421c114cf that was submitted by Russell King.
> 
> No ack the patch.


This is now done in patch #4 "net: fec: reduce interrupts" and you could argue
that it should be squashed into that patch. But I like separating changes
as much as possible.


Russell, this patch and patch #4 will likely need your ack before it will be applied.
Can you take a look please?

http://www.spinics.net/lists/netdev/msg361927.html


Thanks
Troy