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Date:   Wed, 6 Dec 2023 17:58:08 +0000
From:   "Russell King (Oracle)" <linux@armlinux.org.uk>
To:     Maxime Chevallier <maxime.chevallier@bootlin.com>
Cc:     Daniel Golle <daniel@makrotopia.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Chunfeng Yun <chunfeng.yun@mediatek.com>,
        Vinod Koul <vkoul@kernel.org>,
        Kishon Vijay Abraham I <kishon@kernel.org>,
        Felix Fietkau <nbd@nbd.name>, John Crispin <john@phrozen.org>,
        Sean Wang <sean.wang@mediatek.com>,
        Mark Lee <Mark-MC.Lee@mediatek.com>,
        Lorenzo Bianconi <lorenzo@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Alexander Couzens <lynxis@fe80.eu>,
        Qingfang Deng <dqfext@gmail.com>,
        SkyLake Huang <SkyLake.Huang@mediatek.com>,
        Philipp Zabel <p.zabel@pengutronix.de>, netdev@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, linux-phy@lists.infradead.org
Subject: Re: [RFC PATCH v2 5/8] net: pcs: add driver for MediaTek USXGMII PCS
Message-ID: <ZXC2MFn7pVX/KNmJ@shell.armlinux.org.uk>
References: <cover.1701826319.git.daniel@makrotopia.org>
 <3cd8af5e44554c2db2d7898494ee813967206bd9.1701826319.git.daniel@makrotopia.org>
 <20231206105838.069ae288@device.home>
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On Wed, Dec 06, 2023 at 10:58:38AM +0100, Maxime Chevallier wrote:
> On Wed, 6 Dec 2023 01:44:38 +0000
> Daniel Golle <daniel@makrotopia.org> wrote:
> > +	/* Read USXGMII link status */
> > +	state->link = FIELD_GET(RG_PCS_RX_LINK_STATUS,
> > +				mtk_r32(mpcs, RG_PCS_RX_STATUS0));
> > +
> > +	/* Continuously repeat re-configuration sequence until link comes up */
> > +	if (!state->link) {
> > +		mtk_usxgmii_pcs_config(pcs, mpcs->neg_mode,
> > +				       state->interface, NULL, false);
> > +		return;
> 
> .pcs_get_state() isn't called only for link state polling,but also when querying
> the link state from ethtool, from phylink_ethtool_ksettings_get().
> 
> As mtk_usxgmii_pcs_config triggers a pcs reset and reconfiguration, won't this disrupt
> the link ? 

Highly likely if there's a race, but note that mtk_usxgmii_pcs_config()
only gets called if the link is *down*. I guess some IPs need a bit of
kicking to work properly.

-- 
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