On Thu, Jul 24, 2025 at 04:31:25PM +0200, Sebastian Reichel wrote:

According to the Ethernet controller device tree binding "rgmii-id"
means, that the PCB does not have extra long lines to add the required
delays. This is indeed the case for the ROCK 4D.

The problem is, that the Rockchip MAC Linux driver interprets the
interface type differently and abuses the information to configure
RX and TX delays in the MAC using (vendor) properties 'rx_delay' and
'tx_delay'.

When Detlev Casanova upstreamed the ROCK 4D device tree, he used the
correct description for the board ("rgmii-id"). This results in no delays
being configured in the MAC. At the same time the PHY will provide
some delays.

So why can't the MAC be fixed to conform to the requirements that are
well documented for RGMII?

-- 
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