[PATCH v2] arm64: dts: rockchip: Change ethernet TXD timing delay value

[Miguel Jesus Seron Gonzalez]

Hi Dongjin,

On Wed, Aug 20, 2025 at 11:40:44AM +0900, Dongjin Kim wrote:
> Thank you for suggesting me to try 'rgmii-id' again.
>
> I'd remember that 'rgmii-id' didn't work with the very early version of
> the board, however your suggestion works. Let me test the change with
> more boards and submit the new patch when it's done.

I ran into the same problem on an ODROID-M1 board marked
"REV 1.0 20211112", an earlier revision than the 20220613 one in your
patch, running Home Assistant OS (kernel 6.18.52). With the current
tx_delay = <0x4f>, about 6.6% of all TCP segments were retransmitted
at 1000 Mbit/s and larger HTTP transfers stalled.

I tested Chukun's suggestion (phy-mode = "rgmii-id", with tx_delay and
rx_delay removed; the driver reports "init for RGMII_ID") on the same
board, on a 1000 Mbit/s full-duplex link. It works fine on this early
revision as well:

- 3 retransmitted TCP segments out of 24929 (0.012%) over 3 h 49 min
  of uptime, and no RX/TX errors
- 90 sequential requests for large files (22.5 MB in total): no
  failures, 1.4 s in total, the slowest one 47 ms
- 120 parallel requests (75 MB in total): no failures, 1.2 s

For comparison, tx_delay = <0x35> gave 0.03% retransmissions on the
same board.

Are you still planning to send a v3 with rgmii-id? If you don't have
time for it, I'd be happy to send it with Chukun's Suggested-by. Either
way, for the rgmii-id version:

Tested-by: Miguel Jesus Seron Gonzalez <info at gluon.es>

Thanks,
Miguel