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

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Date:   Thu, 3 Sep 2020 23:53:31 +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 11:36:39PM +0200, Marek Vasut wrote:
> On 9/3/20 11:00 PM, Andrew Lunn wrote:
> > 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.
> 
> Which is what ? Details please.

Have you used b4 before?

b4 am 20200903043947.3272453-1-f.fainelli@...il.com

> > 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.
> 
> The FEC MAC is responsible for generating the clock, the PHY clock are
> not part of the clock framework as far as I can tell.

I'm not sure this is true. At least:

https://elixir.bootlin.com/linux/latest/source/arch/arm/boot/dts/imx6ul-kontron-n6x1x-s.dtsi#L123

and there are a few more examples:

imx6ul-14x14-evk.dtsi:			clocks = <&clks IMX6UL_CLK_ENET_REF>;
imx6ul-kontron-n6x1x-s.dtsi:			clocks = <&clks IMX6UL_CLK_ENET_REF>;
imx6ul-kontron-n6x1x-som-common.dtsi:			clocks = <&clks IMX6UL_CLK_ENET_REF>;
imx6ull-myir-mys-6ulx.dtsi:			clocks = <&clks IMX6UL_CLK_ENET_REF>;
imx6ul-phytec-phycore-som.dtsi:			clocks = <&clks IMX6UL_CLK_ENET_REF>;

Maybe it is just IMX6?

      Andrew