Re: [PATCH V3 1/6] dmaengine: zynqmp_dma: Fix PM usage count handling in probe error path

On Fri, Aug 21, 2026 at 09:57:49AM +0530, Golla, Nagendra wrote:
> Hi Frank
>
> On 8/11/2026 9:43 PM, Frank Li wrote:
> > On Mon, Aug 10, 2026 at 03:34:47PM +0530, Golla Nagendra wrote:
> > > When pm_runtime_resume_and_get() succeeds during probe, it increments
> > > the usage count and enables clocks. If a later step (e.g., channel
> > > probe) fails, the error path only called pm_runtime_disable() without
> > > a matching pm_runtime_put_sync(), leaking the reference and the clock
> > > enable.
> > >
> > > Add an else branch to drop the usage count acquired by
> > > pm_runtime_resume_and_get() when runtime PM is still enabled, letting
> > > the PM core suspend/disable clocks on the success-then-later-failure
> > > path.
> > >
> > > Fixes: 64c6f7da8c2c ("dmaengine: zynqmp_dma: Add runtime pm support")
> > > Signed-off-by: Golla Nagendra <[email protected]>
> > > ---
> > > Changes in V3:
> > > - New patch: split from V2 2/3 per Frank Li's review to keep the PM usage
> > >    count fix separate from the per-channel reset changes
> > > ---
> > >   drivers/dma/xilinx/zynqmp_dma.c | 2 ++
> > >   1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/dma/xilinx/zynqmp_dma.c b/drivers/dma/xilinx/zynqmp_dma.c
> > > index f6a812e49ddc..87986f65d24c 100644
> > > --- a/drivers/dma/xilinx/zynqmp_dma.c
> > > +++ b/drivers/dma/xilinx/zynqmp_dma.c
> > > @@ -1152,6 +1152,8 @@ static int zynqmp_dma_probe(struct platform_device *pdev)
> > >   err_disable_pm:
> > >   	if (!pm_runtime_enabled(zdev->dev))
> >
> > You just enable runtime pm above few lines.  Is it for CONFIG_PM?
> >
> > You should check return value of pm_runtime_enable(), or change to use
> >
> > devm_pm_runtime_enable().
> >
> > if devm_runtime_enable() failure, you can direct return. Need check
> > pm_runtime_enabled() here again.
> >
> > >   		zynqmp_dma_runtime_suspend(zdev->dev);
> > > +	else
> > > +		pm_runtime_put_sync(zdev->dev);
> >
> > This one suggest use PM acquire to fix this.
> Thanks for the review
>
> The probe error path already holds a reference from
> pm_runtime_resume_and_get().Using PM_RUNTIME_ACQUIRE_IF_ACTIVE() here would

My means replace pm_runtime_resume_and_get() with PM_RUNTIME_ACQUIRE_IF_ACTIVE()

> acquire a second reference on top of the existing one incrementing the usage
> count to 2, and the guard releasing one at scope exit would still leave one
> leaked reference. The guard is designed for cases where no reference is held
> yet (like the IRQ handler). Here we just need to release the one existing

call pm_runtime_put() before return 0 at probe, which have not hold
runtime pm count for IRQ.

Frank

> reference, so i am using the pm_runtime_put_sync_suspend().
>
> Thanks,
> Nagendra
> >
> > Frank
> >
> > >   	pm_runtime_disable(zdev->dev);
> > >   	return ret;
> > >   }
> > > --
> > > 2.43.7
> > >
>