From: Stefan Eichenberger Add a property to activate a Micrel PHY feature that keeps the preamble enabled before the SFD (Start Frame Delimiter) is transmitted. This allows to workaround broken Ethernet controllers as found on the NXP i.MX8MP. Specifically, errata ERR050694 that states: ENET_QOS: MAC incorrectly discards the received packets when Preamble Byte does not precede SFD or SMD. The bit which disables this feature is not documented in the datasheet from Micrel, but has been found by NXP and Micrel following this discussion: https://community.nxp.com/t5/i-MX-Processors/iMX8MP-eqos-not-working-for-10base-t/m-p/2151032 It has been tested on Verdin iMX8MP from Toradex by forcing the PHY to 10MBit. Withouth this property set, no packets are received. With this property set, reception works fine. Signed-off-by: Stefan Eichenberger --- Documentation/devicetree/bindings/net/micrel.yaml | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/Documentation/devicetree/bindings/net/micrel.yaml b/Documentation/devicetree/bindings/net/micrel.yaml index f48e9b9120ca0..6d6136014cd62 100644 --- a/Documentation/devicetree/bindings/net/micrel.yaml +++ b/Documentation/devicetree/bindings/net/micrel.yaml @@ -165,6 +165,19 @@ allOf: supported clocks: - The RMII reference input clock. Used to determine the XI input clock. + - if: + properties: + compatible: + contains: + const: ethernet-phy-id0022.1640 + then: + properties: + micrel,keep-preamble-before-sfd: + type: boolean + description: | + If set, the PHY keeps sending preamble bits before SFD in + 10BASE-T mode. By default, the PHY removes preamble bits + before SFD. - if: properties: compatible: -- 2.51.0