linux-kernel - Re: [RFC PATCH v2 2/8] phy: add driver for MediaTek pextp 10GE SerDes PHY

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Message-ID: <20231206104448.0774da58@device.home>
Date:   Wed, 6 Dec 2023 10:44:48 +0100
From:   Maxime Chevallier <maxime.chevallier@...tlin.com>
To:     Daniel Golle <daniel@...rotopia.org>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Chunfeng Yun <chunfeng.yun@...iatek.com>,
        Vinod Koul <vkoul@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Felix Fietkau <nbd@....name>, John Crispin <john@...ozen.org>,
        Sean Wang <sean.wang@...iatek.com>,
        Mark Lee <Mark-MC.Lee@...iatek.com>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Alexander Couzens <lynxis@...0.eu>,
        Qingfang Deng <dqfext@...il.com>,
        SkyLake Huang <SkyLake.Huang@...iatek.com>,
        Philipp Zabel <p.zabel@...gutronix.de>, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-phy@...ts.infradead.org
Subject: Re: [RFC PATCH v2 2/8] phy: add driver for MediaTek pextp 10GE
 SerDes PHY

Hello Daniel,

On Wed, 6 Dec 2023 01:44:08 +0000
Daniel Golle <daniel@...rotopia.org> wrote:

> Add driver for MediaTek's pextp 10 Gigabit/s Ethernet SerDes PHY which
> can be found in the MT7988 SoC.
> 
> The PHY can operates only in PHY_MODE_ETHERNET, the submode is one of
> PHY_INTERFACE_MODE_* corresponding to the supported modes:
> 
>  * USXGMII
>  * 10GBase-R
>  * 5GBase-R
>  * 2500Base-X
>  * 1000Base-X
>  * Cisco SGMII (MAC side)
> 
> In order to work-around a performance issue present on the first of
> two PEXTP present in MT7988 special tuning is applied which can be
> selected by adding the mediatek,usxgmii-performance-errata property to
> the device tree node.
> 
> There is no documentation what-so-ever for the pextp registers and
> this driver is based on a GPL licensed implementation found in
> MediaTek's SDK.
> 
> Signed-off-by: Daniel Golle <daniel@...rotopia.org>
> ---

 [...]

> +
> +static int mtk_pextp_power_on(struct phy *phy)
> +{
> +	struct mtk_pextp_phy *pextp = phy_get_drvdata(phy);
> +	int ret;
> +
> +	ret = clk_prepare_enable(pextp->clk[0]);
> +	if (ret)
> +		return ret;
> +
> +	return clk_prepare_enable(pextp->clk[1]);
> +}

clk_bulk operations could be used here

> +static int mtk_pextp_power_off(struct phy *phy)
> +{
> +	struct mtk_pextp_phy *pextp = phy_get_drvdata(phy);
> +
> +	clk_disable_unprepare(pextp->clk[1]);
> +	clk_disable_unprepare(pextp->clk[0]);
> +
> +	return 0;
> +}

Here

> +static const struct phy_ops mtk_pextp_ops = {
> +	.power_on	= mtk_pextp_power_on,
> +	.power_off	= mtk_pextp_power_off,
> +	.set_mode	= mtk_pextp_set_mode,
> +	.reset		= mtk_pextp_reset,
> +	.owner		= THIS_MODULE,
> +};
> +
> +static int mtk_pextp_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct phy_provider *phy_provider;
> +	struct mtk_pextp_phy *pextp;
> +	struct phy *phy;
> +
> +	if (!np)
> +		return -ENODEV;
> +
> +	pextp = devm_kzalloc(&pdev->dev, sizeof(*pextp), GFP_KERNEL);
> +	if (!pextp)
> +		return -ENOMEM;
> +
> +	pextp->base = devm_of_iomap(&pdev->dev, np, 0, NULL);
> +	if (!pextp->base)
> +		return -EIO;
> +
> +	pextp->dev = &pdev->dev;
> +	pextp->clk[0] = devm_clk_get(&pdev->dev, "topxtal");
> +	if (IS_ERR(pextp->clk[0]))
> +		return PTR_ERR(pextp->clk[0]);
> +
> +	pextp->clk[1] = devm_clk_get(&pdev->dev, "xfipll");
> +	if (IS_ERR(pextp->clk[1]))
> +		return PTR_ERR(pextp->clk[1]);

And here as well.

Thanks,

Maxime