Subject: Re: [PATCH 1/1] net: phy: marvell: Fixed handing of delays with plain RGMII interface

From: Marek Behún <[email-masked]>
Date: Tue, 29 Jun 2021 02:21:06 +0200

On Mon, 28 Jun 2021 20:05:19 -0400
Kurt Cancemi <[email-masked]> wrote:

> Well I'm sorry for the noise I was running into a lot of other DPAA
> ethernet related issues and overlooked adding phy-mode = "rgmii-id";
> that fixed the issue. I knew my patch was not correct (as I explained
> in the cover email) but I was not sure why it was necessary but now I
> see it was not necessary I just had "phy-connection-mode" instead of
> "phy-mode".
> 
> May I ask what is the purpose of phy-connection-mode? And why did the

phy-connection-type, not mode

> DPAA driver recognize the PHY interface mode as RGMII ID but the
> Marvell PHY driver didn't?

phy-mode and phy-connection-type are synonyms. phy-mode takes
precedence. Look at drivers/of/of_net.c function of_get_phy_mode().

If your device tree declares both, it can lead to confusion. For
example if dtsi file says
  phy-mode = "rgmii";
and you include this dtsi file but than you say
  phy-connection-type = "rgmii-id";
the kernel code will use rgmii, not rgmii-id, because phy-mode takes
precedence over phy-connection-type.

Marek