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Date:   Wed, 5 May 2021 14:47:19 +0200
From:   Andrew Lunn <andrew@lunn.ch>
To:     Oleksij Rempel <o.rempel@pengutronix.de>
Cc:     Woojung Huh <woojung.huh@microchip.com>,
        UNGLinuxDriver@microchip.com,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, kernel@pengutronix.de,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Russell King <linux@armlinux.org.uk>,
        Michael Grzeschik <m.grzeschik@pengutronix.de>
Subject: Re: [RFC PATCH v1 8/9] net: phy: micrel: ksz886x/ksz8081: add
 cabletest support
Message-ID: <YJKT173qkYZ+Iyp6@lunn.ch>
References: <20210505092025.8785-1-o.rempel@pengutronix.de>
 <20210505092025.8785-9-o.rempel@pengutronix.de>
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On Wed, May 05, 2021 at 11:20:24AM +0200, Oleksij Rempel wrote:
> This patch support for cable test for the ksz886x switches and the
> ksz8081 PHY.
> 
> The patch was tested on a KSZ8873RLL switch with following results:
> 
> - port 1:
>   - cannot detect any distance
>   - provides inverted values
>     (Errata: DS80000830A: "LinkMD does not work on Port 1",
>      http://ww1.microchip.com/downloads/en/DeviceDoc/KSZ8873-Errata-DS80000830A.pdf)
>     - Reports "short" on open or ok.
>     - Reports "ok" on short.

Quite broken. Distance is optional, simply don't report it.  Status is
harder. Reporting ETHTOOL_A_CABLE_RESULT_CODE_OK should really mean
the cable is O.K. If you cannot tell open from O.K, i would return
ETHTOOL_A_CABLE_RESULT_CODE_UNSPEC.

More later.

	Andrew