RE: ibm_newemac tx problem with jumbo frame enabled

[Tirumala Marri <tmarri@apm.com>]

Hi Ben,

>-----Original Message-----
>From: Benjamin Herrenschmidt [mailto:benh@kernel.crashing.org]
>Sent: Thursday, December 08, 2011 2:59 PM
>To: Prashant Bhole
>Cc: linuxppc-dev@ozlabs.org; Tirumala Marri
>Subject: Re: ibm_newemac tx problem with jumbo frame enabled
>
>On Thu, 2011-12-08 at 18:31 +0530, Prashant Bhole wrote:
>
>>
>> I checked RX descriptor status and TX descriptor status and ethtool
>> output.
>> However I don't know about pause packet/frame, how do I check if pause
>> frames are properly negotiated on both sides?
>> I need to try changing pause and FIFO thresholds.
>>
>> ethtool output after disconnection is as follows:
>> # ethtool -S eth0
>> NIC statistics:
>>      rx_packets: 330939
>>      rx_bytes: 804963241
>>      tx_packets: 248554
>>      tx_bytes: 798853638
>>      rx_packets_csum: 330716
>>      tx_packets_csum: 179526
>>      tx_undo: 0
>
> .../...
>
>Ok so none of the error counters seem to trip, odd. No idea what's up,
>you may want to ask the folks at APM (CCed Tirumala).
>
>I wonder also if we are properly enabling the reporting of error
>interrupts... if we got that wrong we may never detect FIFO overruns.
>What you describe really looks like a fifo overrun to me.
>
>Additionally, look at emac_configure(), sees how it configures the pause
>packet thresholds, maybe you can tweak the watermark to be more
>aggressive. Also check that pause is actually enabled (with ethtool) and
>that the PHY negociated it properly (that the link partner supports
>pause frames).
>
I will take a look.
Thx,
Marri