Am Dienstag, den 15.05.2018, 10:18 +0200 schrieb Marco Felsch:
> From: Markus Niebel <markus.nie...@tqs.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

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