From: Andrew Lunn <andrew@lunn.ch>
To: Vladimir Oltean <olteanv@gmail.com>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>,
Florian Fainelli <f.fainelli@gmail.com>,
netdev <netdev@vger.kernel.org>,
"David S. Miller" <davem@davemloft.net>,
open list <linux-kernel@vger.kernel.org>,
Heiner Kallweit <hkallweit1@gmail.com>,
bcm-kernel-feedback-list@broadcom.com, cphealy@gmail.com,
Jose Abreu <joabreu@synopsys.com>
Subject: Re: [PATCH net-next 2/2] net: phy: Add ability to debug RGMII connections
Date: Fri, 18 Oct 2019 18:01:16 +0200 [thread overview]
Message-ID: <20191018160116.GD24810@lunn.ch> (raw)
In-Reply-To: <CA+h21hrqRtxWp1c-8F-9qPPsYxA_w_B_131DRayLBd8xjpOzPg@mail.gmail.com>
> I don't think you are following the big picture of what I am saying. I
> was trying to follow Florian's intention (first make sure I understand
> it) and suggest that the FCS checking code in the patch he submitted
> is not doing what it was intended to. I am getting apparent FCS
> mismatches reported by the program, when I know full well that the MAC
> I am testing on would have dropped those frames were they really
> invalid.
I think this FCS check is not needed. If we feed the MAC random data,
something like 1 in 65535 will have a valid FCS and get passed up.
I've not seen this happen with Ethernet, but i have seen other network
technologies wrong decoding noise on the line and passing up frames
with around 1 in 65536 probability.
But then having the correct Ethertype is another 1 in 65536. So it
seem pretty improbably we do receiver a packet in this method which is
bad. So i would say, any packet received here is a good packet, and
indicate the RGMII mode works. If we don't receive a packet, the mode
is very probably bad.
Andrew
next prev parent reply other threads:[~2019-10-18 16:01 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-15 22:49 [PATCH net-next 0/2] net: phy: Add ability to debug RGMII connections Florian Fainelli
2019-10-15 22:49 ` [PATCH net-next 1/2] net: phy: Use genphy_loopback() by default Florian Fainelli
2019-10-16 13:56 ` Andrew Lunn
2019-10-15 22:49 ` [PATCH net-next 2/2] net: phy: Add ability to debug RGMII connections Florian Fainelli
2019-10-16 8:55 ` Jose Abreu
2019-10-16 14:19 ` Andrew Lunn
2019-10-17 22:06 ` Vladimir Oltean
2019-10-17 22:22 ` Florian Fainelli
2019-10-17 22:49 ` Vladimir Oltean
2019-10-18 13:01 ` Andrew Lunn
2019-10-18 13:09 ` Vladimir Oltean
2019-10-18 13:23 ` Russell King - ARM Linux admin
2019-10-18 13:37 ` Vladimir Oltean
2019-10-18 13:54 ` Russell King - ARM Linux admin
2019-10-18 14:12 ` Vladimir Oltean
2019-10-18 16:01 ` Andrew Lunn [this message]
2019-10-17 19:24 ` [PATCH net-next 0/2] " David Miller
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