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Date:   Sat, 11 Jul 2020 00:54:53 +0200
From:   Andrew Lunn <andrew@lunn.ch>
To:     Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc:     Oleksij Rempel <o.rempel@pengutronix.de>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        David Jander <david@protonic.nl>,
        "David S. Miller" <davem@davemloft.net>, kernel@pengutronix.de,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        Philippe Schenker <philippe.schenker@toradex.com>,
        Russell King <linux@armlinux.org.uk>
Subject: Re: [PATCH net-next v3] net: phy: micrel: add phy-mode support for
 the KSZ9031 PHY
Message-ID: <20200710225453.GK1014141@lunn.ch>
References: <20200422072137.8517-1-o.rempel@pengutronix.de>
 <20200710223610.GC3759@piout.net>
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On Sat, Jul 11, 2020 at 12:36:10AM +0200, Alexandre Belloni wrote:
> Hi Oleksij,
> 
> This patch breaks Ethernet on the sama5d3 Xplained and I have not been
> able to unbreak it.

Hi Alexandre

                        macb0: ethernet@f0028000 {
                                phy-mode = "rgmii";
                                #address-cells = <1>;
                                #size-cells = <0>;
                                status = "okay";

                                ethernet-phy@7 {
                                        reg = <0x7>;
                                };
                        };

So DT says it wants rgmii. How are the delays being added? Could the
bootloader be configuring the PHY into rgmii-id mode, which is now
getting cleared? Or by strapping of pins on the PHY?

Also, looking at macb_main.c is seen:

       if (!(bp->caps & MACB_CAPS_USRIO_DISABLED)) {
                val = 0;
                if (bp->phy_interface == PHY_INTERFACE_MODE_RGMII)
                        val = GEM_BIT(RGMII);
                else if (bp->phy_interface == PHY_INTERFACE_MODE_RMII &&
                         (bp->caps & MACB_CAPS_USRIO_DEFAULT_IS_MII_GMII))
                        val = MACB_BIT(RMII);
                else if (!(bp->caps & MACB_CAPS_USRIO_DEFAULT_IS_MII_GMII))
                        val = MACB_BIT(MII);

                if (bp->caps & MACB_CAPS_USRIO_HAS_CLKEN)
                        val |= MACB_BIT(CLKEN);

                macb_or_gem_writel(bp, USRIO, val);
        }

I don't know if this applies for your hardware, but if you tried
fixing the PHY by setting phy-mode to "rgmii-id", it could be macb
then did not set GEM_BIT(RGMII) and so broken even more?

Rather than bp->phy_interface == PHY_INTERFACE_MODE_RGMII,
phy_interface_mode_is_rgmii() might work better.

      Andrew