From e1b505a60366399d735312ca38b0a6753a684123 Mon Sep 17 00:00:00 2001 From: Markus Niebel Date: Tue, 15 May 2018 10:18:56 +0200 Subject: net: phy: micrel: add 125MHz reference clock workaround 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. Signed-off-by: Markus Niebel [m.felsch@pengutronix.de: fix dt-binding documentation] [m.felsch@pengutronix.de: use already existing result var for read/write] [m.felsch@pengutronix.de: add error handling] [m.felsch@pengutronix.de: add more comments] Signed-off-by: Marco Felsch Reviewed-by: Andrew Lunn Signed-off-by: David S. Miller --- Documentation/devicetree/bindings/net/micrel-ksz90x1.txt | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'Documentation') diff --git a/Documentation/devicetree/bindings/net/micrel-ksz90x1.txt b/Documentation/devicetree/bindings/net/micrel-ksz90x1.txt index 42a248301615..e22d8cfea687 100644 --- a/Documentation/devicetree/bindings/net/micrel-ksz90x1.txt +++ b/Documentation/devicetree/bindings/net/micrel-ksz90x1.txt @@ -57,6 +57,13 @@ KSZ9031: - txd2-skew-ps : Skew control of TX data 2 pad - txd3-skew-ps : Skew control of TX data 3 pad + - micrel,force-master: + Boolean, force phy to master mode. Only set this option if the phy + reference clock provided at CLK125_NDO pin is used as MAC reference + clock because the clock jitter in slave mode is to high (errata#2). + Attention: The link partner must be configurable as slave otherwise + no link will be established. + Examples: mdio { -- cgit v1.2.3-59-g8ed1b