Date:   Thu, 9 Feb 2023 14:54:56 +0100
From:   Andrew Lunn <andrew@lunn.ch>
To:     Md Danish Anwar <a0501179@ti.com>
Cc:     Roger Quadros <rogerq@kernel.org>,
        MD Danish Anwar <danishanwar@ti.com>,
        "Andrew F. Davis" <afd@ti.com>, Suman Anna <s-anna@ti.com>,
        YueHaibing <yuehaibing@huawei.com>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        "David S. Miller" <davem@davemloft.net>, nm@ti.com,
        ssantosh@kernel.org, srk@ti.com, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, netdev@vger.kernel.org,
        linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [EXTERNAL] Re: [EXTERNAL] Re: [EXTERNAL] Re: [PATCH v4 2/2] net:
 ti: icssg-prueth: Add ICSSG ethernet driver
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> Sure, I'll do that. In the list of all phy modes described in [1], I can only
> see phy-mode "rgmii-txid", for which we can return -EINVAL. Is there any other
> phy-mode that requires enabling/disabling TX internal delays? Please let me
> know if any other phy-mode also needs this. I will add check for that as well.

There are 4 phy-modes for RGMII.

rgmii, rgmii-id, rmgii-rxid, rgmii-txid.

rgmii-id, rgmii-txid both require TX delays. If you do that in the MAC
you then need to pass rgmii-rxid and rgmii to the PHY respectively.

rmii and rgmii-rxid requires no TX delays, which your SoC cannot do,
so you need to return -EINVAl,

The interpretation of these properties is all really messy and
historically not very uniformly done. Which is why i recommend the MAC
does nothing, leaving it to the PHY. That generally works since the
PHYs have a pretty uniform implementation. But in your case, you don't
have that option. So i suggest you do what is described above. 

    Andrew