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Subject: Re: CRC errors between mvneta and macb
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     Willy Tarreau <w@1wt.eu>, linux-kernel@vger.kernel.org,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        Antoine Tenart <antoine.tenart@bootlin.com>,
        Gregory CLEMENT <gregory.clement@bootlin.com>,
        Yelena Krivosheev <yelena@marvell.com>,
        Maxime Chevallier <maxime.chevallier@bootlin.com>,
        Nicolas Ferre <nicolas.ferre@microchip.com>,
        netdev@vger.kernel.org
References: <f6ccdfbd-7a67-ae14-5940-c7614cb143e9@sorico.fr>
 <20181019154439.GC24045@1wt.eu>
 <c24489f6-3b9a-f26b-bc7f-b564d5567294@sorico.fr>
 <31385a3b-2196-94d0-7f4f-52e37ee07a28@sorico.fr>
 <20181022181918.GF24112@lunn.ch>
From:   Richard Genoud <richard.genoud@gmail.com>
Message-ID: <3d967432-b526-0cee-ed45-beb27bebd031@sorico.fr>
Date:   Tue, 23 Oct 2018 08:58:10 +0200
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Le 22/10/2018 à 20:19, Andrew Lunn a écrit :
>> I dug more on the subject, and I think I found what Marvell's PHY/MAC
>> doesn't like.
> 
> Hi Richard
> 
> What PHY is being used?
> 
88E1512-NNP2

>> After analyzing the ethernet frame on the Davicom PHY's output (pin
>> TX+), I find out that the FCS errors occurs when the ethernet preamble
>> is longer than 56bits. (something like 58 or 60 bits)
> 
> Some Marvell PHYs have a register bit which might be of interest: Page
> 2, register 16, bit 6.
> 
> 0 = Pad odd nibble preambles in copper receive packets.
> 1 = Pass as is and do not pad odd nibble preambles in
> 
>   Andrew
> 

Thanks, I'll look into that.

Richard