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Date:   Mon, 2 Oct 2023 12:16:12 -0700
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Subject: Re: [RFC PATCH v2 net-next 01/15] phy: introduce phy_get_status() and
 use it to report CDR lock
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To:     Vladimir Oltean <vladimir.oltean@nxp.com>, netdev@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-phy@lists.infradead.org
Cc:     "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Madalin Bucur <madalin.bucur@nxp.com>,
        Ioana Ciornei <ioana.ciornei@nxp.com>,
        Camelia Groza <camelia.groza@nxp.com>,
        Li Yang <leoyang.li@nxp.com>, Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor@kernel.org>,
        Sean Anderson <sean.anderson@seco.com>,
        Maxime Chevallier <maxime.chevallier@bootlin.com>,
        Vinod Koul <vkoul@kernel.org>,
        Kishon Vijay Abraham I <kishon@kernel.org>
References: <20230923134904.3627402-1-vladimir.oltean@nxp.com>
 <20230923134904.3627402-2-vladimir.oltean@nxp.com>
From:   Florian Fainelli <f.fainelli@gmail.com>
In-Reply-To: <20230923134904.3627402-2-vladimir.oltean@nxp.com>
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On 9/23/23 06:48, Vladimir Oltean wrote:
> Some modules, like the MTIP AN/LT block used as a copper backplane PHY
> driver, need this extra information from the SerDes PHY as another
> source of "link up" information.
> 
> Namely, the 25GBase-R PCS does not have a MDIO_CTRL1_LPOWER bit
> implemented in its MDIO_MMD_PCS:MDIO_CTRL1 register. That bit is
> typically set from phy_suspend() or phylink_pcs_disable() implementations,
> and that is supposed to cause a link drop event on the link partner.
> But here it does not happen.
> 
> By implementing the networking phylink_pcs_disable() as phy_power_off(),
> we are able to actually power down the lane in a way that is visible to
> the remote end. Where it is visible is the CDR lock, so we introduce
> PHY_STATUS_TYPE_CDR_LOCK as an extra link indication, we are able to
> detect that condition and signal it to upper layers of the network
> stack.
> 
> A more high-level and generic phy_get_status() operation was chosen
> instead of the more specific phy_get_cdr_lock() alternative, because I
> saw this as being more in the spirit of the generic PHY API.
> Also, phy_get_status() is more extensible and reusable for other
> purposes as well.
> 
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
-- 
Florian