linux-kernel - Re: [PATCH] phy: qualcomm: m31-eusb2: Add runtime pm ops

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Message-ID: <5b7rv52cqu55jn5ku6hy6m7u7yn37i4iviaj4eutlgudw7mpny@w3vhaulnmi2p>
Date: Tue, 28 Oct 2025 09:17:25 -0500
From: Bjorn Andersson <andersson@...nel.org>
To: Prashanth K <prashanth.k@....qualcomm.com>
Cc: Vinod Koul <vkoul@...nel.org>, 
	Kishon Vijay Abraham I <kishon@...nel.org>, linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] phy: qualcomm: m31-eusb2: Add runtime pm ops

On Mon, Oct 27, 2025 at 11:54:58AM +0530, Prashanth K wrote:
> Add runtime power management operation callbacks for M31 EUSB2 PHY.
> Enable/disable the clocks based on the runtime suspend/resume calls.

Please start with describing which problem this solves.

Regards,
Bjorn

> 
> Signed-off-by: Prashanth K <prashanth.k@....qualcomm.com>
> ---
>  drivers/phy/qualcomm/phy-qcom-m31-eusb2.c | 40 +++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
> 
> diff --git a/drivers/phy/qualcomm/phy-qcom-m31-eusb2.c b/drivers/phy/qualcomm/phy-qcom-m31-eusb2.c
> index 0a0d2d9fc846..1aeb5e3de07c 100644
> --- a/drivers/phy/qualcomm/phy-qcom-m31-eusb2.c
> +++ b/drivers/phy/qualcomm/phy-qcom-m31-eusb2.c
> @@ -240,6 +240,34 @@ static const struct phy_ops m31eusb2_phy_gen_ops = {
>  	.owner		= THIS_MODULE,
>  };
>  
> +static int m31eusb2_phy_runtime_suspend(struct device *dev)
> +{
> +	struct m31eusb2_phy *phy = dev_get_drvdata(dev);
> +
> +	dev_dbg(dev, "Suspending M31 eUSB2 Phy\n");
> +	clk_disable_unprepare(phy->clk);
> +
> +	return 0;
> +}
> +
> +static int m31eusb2_phy_runtime_resume(struct device *dev)
> +{
> +	struct m31eusb2_phy *phy = dev_get_drvdata(dev);
> +	int ret = 0;
> +
> +	dev_dbg(dev, "Resuming M31 eUSB2 Phy\n");
> +	ret = clk_prepare_enable(phy->clk);
> +	if (ret)
> +		dev_err(dev, "failed to enable ref clock, %d\n", ret);
> +
> +	return ret;
> +}
> +
> +static const struct dev_pm_ops m31eusb2_phy_pm_ops = {
> +	SET_RUNTIME_PM_OPS(m31eusb2_phy_runtime_suspend,
> +			   m31eusb2_phy_runtime_resume, NULL)
> +};
> +
>  static int m31eusb2_phy_probe(struct platform_device *pdev)
>  {
>  	struct phy_provider *phy_provider;
> @@ -270,6 +298,17 @@ static int m31eusb2_phy_probe(struct platform_device *pdev)
>  		return dev_err_probe(dev, PTR_ERR(phy->clk),
>  				     "failed to get clk\n");
>  
> +	dev_set_drvdata(dev, phy);
> +	pm_runtime_set_active(dev);
> +	pm_runtime_enable(dev);
> +
> +	/*
> +	 * Prevent runtime pm from being ON by default. Users can enable
> +	 * it using power/control in sysfs.
> +	 */
> +	pm_runtime_forbid(dev);
> +
> +
>  	phy->phy = devm_phy_create(dev, NULL, &m31eusb2_phy_gen_ops);
>  	if (IS_ERR(phy->phy))
>  		return dev_err_probe(dev, PTR_ERR(phy->phy),
> @@ -313,6 +352,7 @@ static struct platform_driver m31eusb2_phy_driver = {
>  	.probe = m31eusb2_phy_probe,
>  	.driver = {
>  		.name = "qcom-m31eusb2-phy",
> +		.pm = &m31eusb2_phy_pm_ops,
>  		.of_match_table = m31eusb2_phy_id_table,
>  	},
>  };
> -- 
> 2.34.1
> 
>