linux-kernel - Re: [PATCH 4.19 320/639] ARM: dts: ls1021: Fix SGMII PCS link remaining down after PHY disconnect

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Message-ID: <20200125191333.GG14064@duo.ucw.cz>
Date:   Sat, 25 Jan 2020 20:13:33 +0100
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Vladimir Oltean <olteanv@...il.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Li Yang <leoyang.li@....com>, Shawn Guo <shawnguo@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.19 320/639] ARM: dts: ls1021: Fix SGMII PCS link
 remaining down after PHY disconnect

Hi!

> [ Upstream commit c7861adbe37f576931650ad8ef805e0c47564b9a ]
> 
> Each eTSEC MAC has its own TBI (SGMII) PCS and private MDIO bus.
> But due to a DTS oversight, both SGMII-compatible MACs of the LS1021 SoC
> are pointing towards the same internal PCS. Therefore nobody is
> controlling the internal PCS of eTSEC0.
> 
> Upon initial ndo_open, the SGMII link is ok by virtue of U-boot
> initialization. But upon an ifdown/ifup sequence, the code path from
> ndo_open -> init_phy -> gfar_configure_serdes does not get executed for
> the PCS of eTSEC0 (and is executed twice for MAC eTSEC1). So the SGMII
> link remains down for eTSEC0. On the LS1021A-TWR board, to signal this
> failure condition, the PHY driver keeps printing
> '803x_aneg_done: SGMII link is not ok'.
> 
> Also, it changes compatible of mdio0 to "fsl,etsec2-mdio" to match
> mdio1 device.

It actually changes compatible of both devices.

> +++ b/arch/arm/boot/dts/ls1021a.dtsi
> @@ -584,7 +584,7 @@
>  		};
>  
>  		mdio0: mdio@...4000 {
> -			compatible = "gianfar";
> +			compatible = "fsl,etsec2-mdio";
>  			device_type = "mdio";
>  			#address-cells = <1>;
>  			#size-cells = <0>;
> @@ -592,6 +592,15 @@
>  			      <0x0 0x2d10030 0x0 0x4>;
>  		};
>  
> +		mdio1: mdio@...4000 {
> +			compatible = "fsl,etsec2-mdio";


And they trigger different code in the driver:

                .type = "mdio",
                .compatible = "gianfar",
                .data = &(struct fsl_pq_mdio_data) {
		...
                        .get_tbipa = get_gfar_tbipa_from_mdio,
                },

		.compatible = "fsl,etsec2-mdio",
                .data = &(struct fsl_pq_mdio_data) {
		...
                        .get_tbipa = get_etsec_tbipa,
                },

Are you sure that is good idea for both mainline and stable?

Best regards,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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