[Linux-stm32] [PATCH v2 4/4] arm: dts: stm32: Add Priva E-Measuringbox devicetree

[Andrew Lunn]

> +	/* DP83TD510E PHYs have max MDC rate of 1.75MHz.

Really? That breaks IEEE 802.3, which requires 2.5MHz. Humm, says it
multiple times in the datasheet. Seems like a language lawyer was
involved in the data sheet.

  The DP83TD510E is an ultra-low power Ethernet
  physical layer transceiver compliant with the IEEE
  802.3cg 10Base-T1L specification

I would not be surprised to find that 802.3cg says nothing about MDC,
that is in the base 802.3 standard, which they don't say they are
compliant to.

>        * Since we can't reduce
> +	 * stmmac MDC clock without reducing system bus rate, we need to use
> +	 * gpio based MDIO bus.
> +	 */

At least there is a simple workaround, even if it is much slower than
what you really need.

	Andrew