From: David Miller <davem@davemloft.net>
To: B38611@freescale.com
Cc: B20596@freescale.com, shawn.guo@linaro.org,
netdev@vger.kernel.org, l.stach@pengutronix.de,
r.schwebel@pengutronix.de, lznuaa@gmail.com
Subject: Re: [PATCH v1 1/1 net] net: fec: workaround stop tx during errata ERR006358
Date: Sat, 27 Jul 2013 20:15:18 -0700 (PDT) [thread overview]
Message-ID: <20130727.201518.1008971678857409156.davem@davemloft.net> (raw)
In-Reply-To: <9848F2DB572E5649BA045B288BE08FBE015BE134@039-SN2MPN1-021.039d.mgd.msft.net>
From: Duan Fugang-B38611 <B38611@freescale.com>
Date: Thu, 25 Jul 2013 08:16:23 +0000
> On 25/07/13 14:06, Li Frank wrote:
>>If the ready bit in the transmit buffer descriptor (TxBD[R]) is previously detected as not set during a prior frame transmission, then the ENET_TDAR[TDAR] bit is cleared at a later time, even if additional TxBDs were added to the ring and the ENET_TDAR[TDAR] bit is set. This results in frames not being transmitted until there is a 0-to-1 transition on ENET_TDAR[TDAR].
>>
>>Workarounds:
>>code can use the transmit frame interrupt flag (ENET_EIR[TXF]) as a method to detect whether the ENET has completed transmission and the ENET_TDAR[TDAR] has been cleared. If ENET_TDAR[TDAR] is detected as cleared when packets are queued and waiting for transmit, then a write to the TDAR bit will restart TxBD processing.
>>
>>This case main happen when loading is light. A ethernet package may not send out utile next package put into tx queue.
>>
>>How to test:
>>while [ true ]
>>do
>> ping <IP> -s 10000 -w 4
>> ping <IP> -s 6000 -w 2
>> ping <IP> -s 4000 -w 2
>> ping <IP> -s 10000 -w 2
>>done
>>
>>You will see below result in overnight test.
>>
>>6008 bytes from 10.192.242.116: seq=1 ttl=128 time=0.722 ms
>>4008 bytes from 10.192.242.116: seq=0 ttl=128 time=1001.008 ms
>>4008 bytes from 10.192.242.116: seq=1 ttl=128 time=1.010 ms
>>10008 bytes from 10.192.242.116: seq=0 ttl=128 time=0.896 ms
>>
>>After apply this patch, >1000ms delay disappear.
>>
>>Signed-off-by: Frank Li <Frank.Li@freescale.com>
>
> Acked-by: Fugang Duan <B38611@freescale.com>
Applied, thanks.
prev parent reply other threads:[~2013-07-28 3:15 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-25 6:05 [PATCH v1 1/1 net] net: fec: workaround stop tx during errata ERR006358 Frank Li
2013-07-25 8:16 ` Duan Fugang-B38611
2013-07-28 3:15 ` David Miller [this message]
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