netdev - Re: [RESEND PATCH v2 1/1] net: phy: micrel: add 125MHz reference clock workaround

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Date:   Tue, 15 May 2018 20:11:13 +0200
From:   Markus Niebel <niebelm@...c.de>
To:     Marco Felsch <m.felsch@...gutronix.de>, robh+dt@...nel.org,
        mark.rutland@....com, andrew@...n.ch, f.fainelli@...il.com
Cc:     netdev@...r.kernel.org, devicetree@...r.kernel.org,
        kernel@...gutronix.de, Markus.Niebel@...group.com
Subject: Re: [RESEND PATCH v2 1/1] net: phy: micrel: add 125MHz reference
 clock workaround

Am Dienstag, den 15.05.2018, 10:18 +0200 schrieb Marco Felsch:
> From: Markus Niebel <Markus.Niebel@....de>
> 
> The micrel KSZ9031 phy has a optional clock pin (CLK125_NDO) which can be
> used as reference clock for the MAC unit. The clock signal must meet the
> RGMII requirements to ensure the correct data transmission between the
> MAC and the PHY. The KSZ9031 phy does not fulfill the duty cycle
> requirement if the phy is configured as slave. For a complete
> describtion look at the errata sheets: DS80000691D or DS80000692D.
> 
> The errata sheet recommends to force the phy into master mode whenever
> there is a 1000Base-T link-up as work around. Only set the
> "micrel,force-master" property if you use the phy reference clock provided
> by CLK125_NDO pin as MAC reference clock in your application.
> 
> Attenation, this workaround is only usable if the link partner can
> be configured to slave mode for 1000Base-T.
> 
Thank you for documenting and bringing it mainline, should be clear enough what the
modification is meant for.

Markus