Re: [PATCH v8 3/6] phy: fsl-imx8mq-usb: add runtime PM support

On Fri, Jul 31, 2026 at 04:11:21PM +0800, Xu Yang wrote:
> From: Xu Yang <[email protected]>
>
> Add runtime PM support to ensure the PHY clocks are properly gated
> when the PHY is not in use, reducing power consumption.
>
> Clock management is moved from power_on()/power_off() callbacks into
> the runtime_resume()/runtime_suspend() callbacks respectively. The PHY
> subsystem core already holds a runtime PM reference around init() and
> power_on/off() calls, so no explicit clock handling is needed there.
>
> Use devm_clk_get_enabled() and devm_clk_get_optional_enabled() in
> probe() to keep clocks enabled initially. This ensures the PHY remains
> functional when CONFIG_PM is disabled, where runtime suspend/resume
> callbacks are never invoked.
>
> In tca_blk_typec_switch_set(), replace the manual clk_prepare_enable()
> / clk_disable_unprepare() pair with PM_RUNTIME_ACQUIRE_IF_ENABLED() to
> guard register access against a concurrently suspended PHY.
>
> Move devm_regulator_get() before pm_runtime_enable() to avoid having
> to clean up runtime PM state on regulator acquisition failure.
>
> In remove(), call pm_runtime_get_sync() before pm_runtime_disable() to
> ensure the PHY is resumed and clocks are enabled before the devres
> teardown disables them.
>
> Signed-off-by: Xu Yang <[email protected]>
>
> ---
> Changes in v8:
>  - fix if condition in imx8mq_usb_phy_remove()
> Changes in v7:
>  - replase PM_RUNTIME_ACQUIRE()  with PM_RUNTIME_ACQUIRE_IF_ENABLED()
>  - use non-devm PM runtime callback because it's hard to avoid double clock
>    disable issue when probe fails or remove the driver
>  - improve commit message
> Changes in v6:
>  - use devm_pm_runtime_enable() to disable runtime PM when probe fails
>  - simply pm_runtime_get_sync/disable/put_noidle() to pm_runtime_resume()
> Changes in v5:
>  - use non-devm PM runtime callback to correctly enable/disable clocks
>    when unbind the device
> Changes in v4:
>  - replace guard() with PM_RUNTIME_ACQUIRE()
> Changes in v3:
>  - new patch
> ---
>  drivers/phy/freescale/phy-fsl-imx8mq-usb.c | 103 +++++++++++++++++++++--------
>  1 file changed, 74 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/phy/freescale/phy-fsl-imx8mq-usb.c b/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
> index 3a5788c609e1..42de2cff4d5f 100644
> --- a/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
> +++ b/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
> @@ -9,6 +9,7 @@
>  #include <linux/of.h>
>  #include <linux/phy/phy.h>
>  #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/regulator/consumer.h>
>  #include <linux/usb/typec_mux.h>
>
> @@ -136,17 +137,15 @@ static int tca_blk_typec_switch_set(struct typec_switch_dev *sw,
>  {
>  	struct imx8mq_usb_phy *imx_phy = typec_switch_get_drvdata(sw);
>  	struct tca_blk *tca = imx_phy->tca;
> -	int ret;
>
>  	if (tca->orientation == orientation)
>  		return 0;
>
> -	ret = clk_prepare_enable(imx_phy->clk);
> -	if (ret)
> -		return ret;
> +	PM_RUNTIME_ACQUIRE_IF_ENABLED(&imx_phy->phy->dev, pm);
> +	if (PM_RUNTIME_ACQUIRE_ERR(&pm))
> +		return -ENXIO;
>
>  	tca_blk_orientation_set(tca, orientation);
> -	clk_disable_unprepare(imx_phy->clk);
>
>  	return 0;
>  }
> @@ -620,16 +619,6 @@ static int imx8mq_phy_power_on(struct phy *phy)
>  	if (ret)
>  		return ret;
>
> -	ret = clk_prepare_enable(imx_phy->clk);
> -	if (ret)
> -		return ret;
> -
> -	ret = clk_prepare_enable(imx_phy->alt_clk);
> -	if (ret) {
> -		clk_disable_unprepare(imx_phy->clk);
> -		return ret;
> -	}
> -
>  	/* Disable rx term override */
>  	value = readl(imx_phy->base + PHY_CTRL6);
>  	value &= ~PHY_CTRL6_RXTERM_OVERRIDE_SEL;
> @@ -648,8 +637,6 @@ static int imx8mq_phy_power_off(struct phy *phy)
>  	value |= PHY_CTRL6_RXTERM_OVERRIDE_SEL;
>  	writel(value, imx_phy->base + PHY_CTRL6);
>
> -	clk_disable_unprepare(imx_phy->alt_clk);
> -	clk_disable_unprepare(imx_phy->clk);
>  	regulator_disable(imx_phy->vbus);
>
>  	return 0;
> @@ -686,6 +673,7 @@ static int imx8mq_usb_phy_probe(struct platform_device *pdev)
>  	struct device *dev = &pdev->dev;
>  	struct imx8mq_usb_phy *imx_phy;
>  	const struct phy_ops *phy_ops;
> +	int ret;
>
>  	imx_phy = devm_kzalloc(dev, sizeof(*imx_phy), GFP_KERNEL);
>  	if (!imx_phy)
> @@ -693,13 +681,13 @@ static int imx8mq_usb_phy_probe(struct platform_device *pdev)
>
>  	platform_set_drvdata(pdev, imx_phy);
>
> -	imx_phy->clk = devm_clk_get(dev, "phy");
> +	imx_phy->clk = devm_clk_get_enabled(dev, "phy");
>  	if (IS_ERR(imx_phy->clk)) {
>  		dev_err(dev, "failed to get imx8mq usb phy clock\n");
>  		return PTR_ERR(imx_phy->clk);
>  	}
>
> -	imx_phy->alt_clk = devm_clk_get_optional(dev, "alt");
> +	imx_phy->alt_clk = devm_clk_get_optional_enabled(dev, "alt");
>  	if (IS_ERR(imx_phy->alt_clk))
>  		return dev_err_probe(dev, PTR_ERR(imx_phy->alt_clk),
>  				    "Failed to get alt clk\n");
> @@ -708,44 +696,101 @@ static int imx8mq_usb_phy_probe(struct platform_device *pdev)
>  	if (IS_ERR(imx_phy->base))
>  		return PTR_ERR(imx_phy->base);
>
> +	imx_phy->vbus = devm_regulator_get(dev, "vbus");
> +	if (IS_ERR(imx_phy->vbus))
> +		return dev_err_probe(dev, PTR_ERR(imx_phy->vbus), "failed to get vbus\n");
> +
>  	phy_ops = of_device_get_match_data(dev);
>  	if (!phy_ops)
>  		return -EINVAL;
>
> -	imx_phy->phy = devm_phy_create(dev, NULL, phy_ops);
> -	if (IS_ERR(imx_phy->phy))
> -		return PTR_ERR(imx_phy->phy);
> +	pm_runtime_set_active(dev);
> +	pm_runtime_enable(dev);

does devm_pm_runtime_set_active_enabled() work?

Frank
>
> -	imx_phy->vbus = devm_regulator_get(dev, "vbus");
> -	if (IS_ERR(imx_phy->vbus))
> -		return dev_err_probe(dev, PTR_ERR(imx_phy->vbus), "failed to get vbus\n");
> +	imx_phy->phy = devm_phy_create(dev, NULL, phy_ops);
> +	if (IS_ERR(imx_phy->phy)) {
> +		ret = dev_err_probe(dev, PTR_ERR(imx_phy->phy),
> +				    "failed to create PHY\n");
> +		goto disable_rpm;
> +	}
>
>  	phy_set_drvdata(imx_phy->phy, imx_phy);
>
>  	imx_phy->tca = imx95_usb_phy_get_tca(pdev, imx_phy);
> -	if (IS_ERR(imx_phy->tca))
> -		return dev_err_probe(dev, PTR_ERR(imx_phy->tca),
> -					"failed to get tca\n");
> +	if (IS_ERR(imx_phy->tca)) {
> +		ret = dev_err_probe(dev, PTR_ERR(imx_phy->tca),
> +				    "failed to get tca\n");
> +		goto disable_rpm;
> +	}
>
>  	imx8m_get_phy_tuning_data(imx_phy);
>  	device_set_wakeup_capable(dev, true);
>
>  	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
> +	if (IS_ERR(phy_provider)) {
> +		ret = dev_err_probe(dev, PTR_ERR(phy_provider),
> +				    "failed to register phy provider\n");
> +		goto disable_rpm;
> +	}
>
> -	return PTR_ERR_OR_ZERO(phy_provider);
> +	return 0;
> +
> +disable_rpm:
> +	pm_runtime_disable(dev);
> +	return ret;
>  }
>
>  static void imx8mq_usb_phy_remove(struct platform_device *pdev)
>  {
> +	struct device *dev = &pdev->dev;
> +	int ret;
> +
> +	ret = pm_runtime_get_sync(dev);
> +	if (ret < 0)
> +		dev_warn(dev, "failed to resume on remove: %d\n", ret);
> +
> +	pm_runtime_disable(dev);
> +	pm_runtime_put_noidle(dev);
> +}
> +
> +static int imx8mq_usb_phy_runtime_suspend(struct device *dev)
> +{
> +	struct imx8mq_usb_phy *imx_phy = dev_get_drvdata(dev);
> +
> +	clk_disable_unprepare(imx_phy->alt_clk);
> +	clk_disable_unprepare(imx_phy->clk);
> +
> +	return 0;
> +}
> +
> +static int imx8mq_usb_phy_runtime_resume(struct device *dev)
> +{
> +	struct imx8mq_usb_phy *imx_phy = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = clk_prepare_enable(imx_phy->clk);
> +	if (ret)
> +		return ret;
>
> +	ret = clk_prepare_enable(imx_phy->alt_clk);
> +	if (ret) {
> +		clk_disable_unprepare(imx_phy->clk);
> +		return ret;
> +	}
> +
> +	return 0;
>  }
>
> +static DEFINE_RUNTIME_DEV_PM_OPS(imx8mq_usb_phy_pm_ops, imx8mq_usb_phy_runtime_suspend,
> +				 imx8mq_usb_phy_runtime_resume, NULL);
> +
>  static struct platform_driver imx8mq_usb_phy_driver = {
>  	.probe	= imx8mq_usb_phy_probe,
>  	.remove = imx8mq_usb_phy_remove,
>  	.driver = {
>  		.name	= "imx8mq-usb-phy",
>  		.of_match_table	= imx8mq_usb_phy_of_match,
> +		.pm = pm_ptr(&imx8mq_usb_phy_pm_ops),
>  		.suppress_bind_attrs = true,
>  	}
>  };
>
> --
> 2.34.1
>
>