Re: [PATCH] coresight: Fix clock refcount imbalance on platform probe failure

[Jie Gan]

On 9/9/2026 5:28 PM, Leo Yan wrote:
Hi Leo,

> Hi Jie,
>
> Thanks for fixing! It is shame that my single patch caused issues both
> in driver's probe and remove - I have to admit that I don't understand
> runtime PM's state machine.
>
> TBC, this patch only fixes probe. The driver's remove is fixed in:
> https://lore.kernel.org/linux-arm-kernel/20260710-fix-clock-refcount-unbalance-v3-0-a37a1fb17981@xxxxxxxxxxxxxxxx/
>
> The series above and this patch should be picked up together so can
> have complete fix.
>
> > The probe wrapper then unconditionally calls pm_runtime_put()
> > regardless of whether the inner probe succeeded, so on failure this
> > also fires runtime_suspend() and disables the same clocks a first
> > time.
>
> pm_runtime_put() can be used for success case, but for the failure
> case, we should disable the runtime PM but not release reference:
> https://docs.kernel.org/power/runtime_pm.html#runtime-pm-initialization-device-probing-and-removal
>
> > @@ -632,11 +632,14 @@ static int catu_platform_probe(struct platform_device *pdev)
> >   	pm_runtime_enable(&pdev->dev);
> >   
> >   	ret = __catu_probe(&pdev->dev, res);
> > -	pm_runtime_put(&pdev->dev);
> > -	if (ret)
> > +	if (ret) {
> > +		pm_runtime_put_noidle(&pdev->dev);
> >   		pm_runtime_disable(&pdev->dev);
>
> Nitpick: please reverse the sequence between pm_runtime_put_noidle()
> and pm_runtime_disable(). As we need to first disable runtime PM for
> the device, then release usage reference.
>
> Since the driver core will reset device's active state, AI told me that
> calling pm_runtime_set_suspended() is redundant. It is still good to
> explicitly call it for bookkeeping. This can be aligned with the change
> in driver remove.
>
> Thus, please update the flow:
>
>          pm_runtime_disable(&pdev->dev);
>          pm_runtime_set_suspended(dev);
>          pm_runtime_put_noidle(&pdev->dev);
>
> With the update:

will update the flow in next version.
Thanks for reviewing.

Jie

> Reviewed-by: Leo Yan <leo.yan@xxxxxxx>