Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 22 Oct 2018 20:19:18 +0200
From:   Andrew Lunn <andrew@lunn.ch>
To:     Richard Genoud <richard.genoud@gmail.com>
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
Subject: Re: CRC errors between mvneta and macb
Message-ID: <20181022181918.GF24112@lunn.ch>
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>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <31385a3b-2196-94d0-7f4f-52e37ee07a28@sorico.fr>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

> 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?

> 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