[RFC] sunxi phy-mode rgmii-id

[Heinrich Schuchardt]

Hello Joe, hello Jagan,

since Linux patch
bbc4d71d6354 ("net: phy: realtek: fix rtl8211e rx/tx delay config")
i.e. since v5.8.15 or v5.9 many if not all Sunxi A64, H6, H5 boards
require phy-mode = "rgmii-id" to provide network in Linux

The U-Boot device-tree is the fallback in the UEFI sub-system if no
other device-tree is provided. So it would make sense to adjust the
U-Boot device-trees too.

The Linux patch has specifically changed the values corresponding to our
U-Boot defines:

#define MIIM_RTL8211E_CONFREG_TXD               0x0002
#define MIIM_RTL8211E_CONFREG_RXD               0x0004

At least my experience with the NanoPi Neo 2 and the Pine64 A64 LTS
indicates that setting phy-mode = "rgmii-id" in the device-tree does not
stop the operation of the network even if the driver is not adjusted.

To avoid breaking boards like Linux did we should change the
device-trees before or in sync with drivers/net/phy/realtek.c.

Best regards

Heinrich