[PATCH] usb: dwc3-am62: shut down refclk on remove

[PATCH] usb: dwc3-am62: shut down refclk on remove

[Myeonghun Pak]

dwc3_ti_remove() relies on pm_runtime_put_sync() to invoke the
runtime-suspend callback and disable the USB2 reference clock.  The
callback is not guaranteed to run: autosuspend may defer it, and a
reference held by pm_runtime_forbid() keeps the usage count above zero.
The following pm_runtime_disable() then cancels pending work while the
clock remains enabled.

Balance only the reference acquired by remove without requesting a suspend,
then disable runtime PM to drain any operation in progress.  Disable the
clock explicitly when the stable runtime status shows that the device was
not already suspended.  This also handles CONFIG_PM=n, where the runtime-PM
calls are stubs, without double-disabling the clock after a failed resume.

This issue was identified during our ongoing static-analysis research while
reviewing kernel code.

Fixes: 6661befe4100 ("usb: dwc3-am62: fix module unload/reload behavior")
Assisted-by: OpenAI:GPT-5.6
Co-developed-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
---
 drivers/usb/dwc3/dwc3-am62.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/dwc3-am62.c b/drivers/usb/dwc3/dwc3-am62.c
index 632634d6e..2fb9e088f 100644
--- a/drivers/usb/dwc3/dwc3-am62.c
+++ b/drivers/usb/dwc3/dwc3-am62.c
@@ -319,9 +319,11 @@ static void dwc3_ti_remove(struct platform_device *pdev)
 	reg &= ~USBSS_MODE_VALID;
 	dwc3_ti_writel(am62, USBSS_MODE_CONTROL, reg);
 
-	pm_runtime_put_sync(dev);
+	pm_runtime_put_noidle(dev);
 	pm_runtime_disable(dev);
 	pm_runtime_dont_use_autosuspend(dev);
+	if (!pm_runtime_status_suspended(dev))
+		clk_disable_unprepare(am62->usb2_refclk);
 	pm_runtime_set_suspended(dev);
 }
 
-- 
2.47.1

Re: [PATCH] usb: dwc3-am62: shut down refclk on remove

[Thinh Nguyen]

On Sat, Sep 12, 2026, Myeonghun Pak wrote:
> dwc3_ti_remove() relies on pm_runtime_put_sync() to invoke the
> runtime-suspend callback and disable the USB2 reference clock.  The
> callback is not guaranteed to run: autosuspend may defer it, and a
> reference held by pm_runtime_forbid() keeps the usage count above zero.
> The following pm_runtime_disable() then cancels pending work while the
> clock remains enabled.
> 
> Balance only the reference acquired by remove without requesting a suspend,
> then disable runtime PM to drain any operation in progress.  Disable the
> clock explicitly when the stable runtime status shows that the device was
> not already suspended.  This also handles CONFIG_PM=n, where the runtime-PM
> calls are stubs, without double-disabling the clock after a failed resume.
> 
> This issue was identified during our ongoing static-analysis research while
> reviewing kernel code.
> 
> Fixes: 6661befe4100 ("usb: dwc3-am62: fix module unload/reload behavior")
> Assisted-by: OpenAI:GPT-5.6
> Co-developed-by: Ijae Kim <ae878000@gmail.com>
> Signed-off-by: Ijae Kim <ae878000@gmail.com>
> Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
> ---
>  drivers/usb/dwc3/dwc3-am62.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-am62.c b/drivers/usb/dwc3/dwc3-am62.c
> index 632634d6e..2fb9e088f 100644
> --- a/drivers/usb/dwc3/dwc3-am62.c
> +++ b/drivers/usb/dwc3/dwc3-am62.c
> @@ -319,9 +319,11 @@ static void dwc3_ti_remove(struct platform_device *pdev)
>  	reg &= ~USBSS_MODE_VALID;
>  	dwc3_ti_writel(am62, USBSS_MODE_CONTROL, reg);
>  
> -	pm_runtime_put_sync(dev);
> +	pm_runtime_put_noidle(dev);
>  	pm_runtime_disable(dev);
>  	pm_runtime_dont_use_autosuspend(dev);
> +	if (!pm_runtime_status_suspended(dev))
> +		clk_disable_unprepare(am62->usb2_refclk);
>  	pm_runtime_set_suspended(dev);
>  }
>  
> -- 
> 2.47.1
> 

Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>

Please also add Cc stable.

Thanks,
Thinh