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

On Tue, Aug 04, 2026 at 06:41:56PM +0800, Xu Yang wrote:
> On Fri, Jul 31, 2026 at 09:42:39AM -0500, Frank Li wrote:
> > 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?
>
> Compared to devm_pm_runtime_enable(), devm_pm_runtime_set_active_enabled() just do
> pm_runtime_set_active() before devm_pm_runtime_enable() and pm_runtime_set_suspended()
> after pm_runtime_disable().

Okay, Anyways, we need better method to handle this in future. Anyway

Reviewed-by: Frank Li <[email protected]>

>
> It doesn't change the reality that the device may be runtime suspended before undo
> devm_clk_get_enabled(), that is clk_disable_unprepare().
>
> In V4, V3, I used devm_pm_runtime_set_active_enabled(), but it didn't work:
> https://patchwork.kernel.org/project/imx/patch/[email protected]/
> https://patchwork.kernel.org/project/imx/patch/[email protected]/
>
> Thanks,
> Xu Yang
>