From mboxrd@z Thu Jan  1 00:00:00 1970
From: Johan Hovold <johan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Subject: Re: [PATCH] dma: cpp41: Fix handling of error path
Date: Mon, 14 Nov 2016 15:59:00 +0100
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To: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
Cc: Johan Hovold <johan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Vinod Koul <vinod.koul-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Bin Liu <b-liu-l0cyMroinI0@public.gmane.org>, Daniel Mack <zonque-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Felipe Balbi <felipe.balbi-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>, George Cherian <george.cherian-l0cyMroinI0@public.gmane.org>, Peter Ujfalusi <peter.ujfalusi-l0cyMroinI0@public.gmane.org>, Sebastian Andrzej Siewior <bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, dmaengine-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
List-Id: linux-omap@vger.kernel.org

On Mon, Nov 14, 2016 at 06:47:31AM -0800, Tony Lindgren wrote:
> Hi,
> 
> * Johan Hovold <johan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> [161114 06:35]:
> > On Fri, Nov 11, 2016 at 11:28:52AM -0800, Tony Lindgren wrote:
> > > If we return early on pm_runtime_get() error, we need to also call
> > > pm_runtime_put_noidle() as pointed out in a musb related thread
> > > by Johan Hovold <johan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>. This is to keep the PM runtime
> > > use counts happy.
> > > 
> > > Fixes: fdea2d09b997 ("dmaengine: cppi41: Add basic PM runtime support")
> > > Cc: Johan Hovold <johan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> > > Signed-off-by: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
> > > ---
> > >  drivers/dma/cppi41.c | 11 +++++++++--
> > >  1 file changed, 9 insertions(+), 2 deletions(-)
> >  
> > > @@ -466,6 +472,7 @@ static void cppi41_dma_issue_pending(struct dma_chan *chan)
> > >  
> > >  	error = pm_runtime_get(cdd->ddev.dev);
> > >  	if ((error != -EINPROGRESS) && error < 0) {
> > > +		pm_runtime_put_noidle(cdd->ddev.dev);
> > >  		dev_err(cdd->ddev.dev, "Failed to pm_runtime_get: %i\n",
> > >  			error);
> > 
> > Will this chunk not introduce rather than fix an imbalance, though? An
> > error is never returned above, and the corresponding put is done
> > unconditionally as far as I can tell.
> 
> There is already an early return in cppi41_dma_issue_pending() on
> error.

Indeed, but before

	"dma: cppi41: Fix unpaired pm runtime when only a USB hub is
        connected"

from last week, the corresponding put in cppi41_irq() was done
unconditionally and would have required an unconditional get here.

Thanks,
Johan
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