netdev - Re: [PATCH] net: fec: Fix PHY init after phy_reset_after_clk

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Message-ID: <20200903210011.GD3112546@lunn.ch>
Date:   Thu, 3 Sep 2020 23:00:11 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Marek Vasut <marex@...x.de>
Cc:     netdev@...r.kernel.org,
        Christoph Niedermaier <cniedermaier@...electronics.com>,
        "David S . Miller" <davem@...emloft.net>,
        NXP Linux Team <linux-imx@....com>,
        Richard Leitner <richard.leitner@...data.com>,
        Shawn Guo <shawnguo@...nel.org>
Subject: Re: [PATCH] net: fec: Fix PHY init after phy_reset_after_clk_enable()

On Thu, Sep 03, 2020 at 10:27:12PM +0200, Marek Vasut wrote:
> The phy_reset_after_clk_enable() does a PHY reset, which means the PHY
> loses its register settings. The fec_enet_mii_probe() starts the PHY
> and does the necessary calls to configure the PHY via PHY framework,
> and loads the correct register settings into the PHY. Therefore,
> fec_enet_mii_probe() should be called only after the PHY has been
> reset, not before as it is now.

I think this patch is related to what Florian is currently doing with
PHY clocks.

I think a better fix for the original problem is for the SMSC PHY
driver to control the clock itself. If it clk_prepare_enables() the
clock, it knows it will not be shut off again by the FEC run time
power management.

All this phy_reset_after_clk_enable() can then go away.

    Andrew